Regarding the doctrine of the Trinity, note that sola scriptura shows that Jesus Christ is God (John 1:1,14, John 10:30, John 20:28, Titus 2:13, Philippians 2:6, Matthew 1:23). And He is uncreated God, just as God the Father is uncreated God. For everything created was created by Jesus (John 1:3, Colossians 1:16-17). Because Jesus is uncreated, there was never a time when He was not. He has always existed. He is YHWH the Holy One, from everlasting (Habakkuk 1:12a, Acts 3:14, Micah 5:2c). He is YHWH the only Savior (Isaiah 43:11, Titus 2:13), YHWH the good shepherd (Psalms 23:1, John 10:11, Mark 10:18), YHWH who will set His feet on the Mount of Olives at His return (Zechariah 14:3-4, Acts 1:11-12), YHWH the first and last (Isaiah 44:6, Revelation 2:8), YHWH the great I AM (Exodus 3:14, John 8:58), the great God (Titus 2:13), the mighty God (Isaiah 9:6), one God with God the Father (John 10:30, John 20:28), equal in divinity with God the Father (Philippians 2:6).
Just as the Trinity of Father, Son, and Holy Spirit (Matthew 28:19) is the three distinct, coexisting Persons (Mark 1:9-11) of God the Father (Galatians 1:3), God the Son (Hebrews 1:8), and God the Holy Spirit (cf. Mark 13:11 and Matthew 10:19-20; Acts 5:3-4), so the Trinity is YHWH the Father, YHWH the Son, and YHWH the Holy Spirit. For YHWH is the only God (Isaiah 45:5-6). He has always been and forever will be the only God (Isaiah 43:10b).
What you said above is what Scripture says. But in the early Church, they argued about what it meant. And what they came to agree on is Sacred Tradition. From the CCC:
During the first centuries the Church sought to clarify her Trinitarian faith, both to deepen her own understanding of the faith and to defend it against the errors that were deforming it. This clarification was the work of the early councils, aided by the theological work of the Church Fathers and sustained by the Christian people's sense of the faith.
251 In order to articulate the dogma of the Trinity, the Church had to develop her own terminology with the help of certain notions of philosophical origin: "substance", "person" or "hypostasis", "relation" and so on. In doing this, she did not submit the faith to human wisdom, but gave a new and unprecedented meaning to these terms, which from then on would be used to signify an ineffable mystery, "infinitely beyond all that we can humanly understand".82
252 The Church uses (I) the term "substance" (rendered also at times by "essence" or "nature") to designate the divine being in its unity, (II) the term "person" or "hypostasis" to designate the Father, Son and Holy Spirit in the real distinction among them, and (III) the term "relation" to designate the fact that their distinction lies in the relationship of each to the others.
The dogma of the Holy Trinity
253 The Trinity is One. We do not confess three Gods, but one God in three persons, the "consubstantial Trinity".83 The divine persons do not share the one divinity among themselves but each of them is God whole and entire: "The Father is that which the Son is, the Son that which the Father is, the Father and the Son that which the Holy Spirit is, i.e. by nature one God."84 In the words of the Fourth Lateran Council (1215), "Each of the persons is that supreme reality, viz., the divine substance, essence or nature."85
254 The divine persons are really distinct from one another. "God is one but not solitary."86 "Father", "Son", "Holy Spirit" are not simply names designating modalities of the divine being, for they are really distinct from one another: "He is not the Father who is the Son, nor is the Son he who is the Father, nor is the Holy Spirit he who is the Father or the Son."87 They are distinct from one another in their relations of origin: "It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds."88 The divine Unity is Triune.
255 The divine persons are relative to one another. Because it does not divide the divine unity, the real distinction of the persons from one another resides solely in the relationships which relate them to one another: "In the relational names of the persons the Father is related to the Son, the Son to the Father, and the Holy Spirit to both. While they are called three persons in view of their relations, we believe in one nature or substance."89Indeed "everything (in them) is one where there is no opposition of relationship."90 "Because of that unity the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son."91
256 St. Gregory of Nazianzus, also called "the Theologian", entrusts this summary of Trinitarian faith to the catechumens of Constantinople:
Above all guard for me this great deposit of faith for which I live and fight, which I want to take with me as a companion, and which makes me bear all evils and despise all pleasures: I mean the profession of faith in the Father and the Son and the Holy Spirit. I entrust it to you today. By it I am soon going to plunge you into water and raise you up from it. I give it to you as the companion and patron of your whole life. I give you but one divinity and power, existing one in three, and containing the three in a distinct way. Divinity without disparity of substance or nature, without superior degree that raises up or inferior degree that casts down. . . the infinite co-naturality of three infinites. Each person considered in himself is entirely God. . . the three considered together. . . I have not even begun to think of unity when the Trinity bathes me in its splendor. I have not even begun to think of the Trinity when unity grasps me. . .92
What is meant is what is said.
That is, sola scriptura shows in John 6:53-57 that all Christians, for their ultimate salvation, must eat the bread of Communion (Matthew 26:26), and drink the wine of Communion (Matthew 26:27-29), which actually become the body and blood of Jesus Christ (1 Corinthians 11:27-30), in some spiritual manner (John 6:63).
I won't speak to the fact that all Christians are not in Communion. But I will say that there is a lot of disagreement about what John 6 means, but the Early Church wrote extensively about it, that it is really the body and blood, soul and divinity of Christ present in the Eucharist, just to be brief.
"Discerning the Lord's body" (1 Corinthians 11:29) means that when Christians partake of Communion (1 Corinthians 11:23-29), they must discern that the bread and wine are the actual body and blood of Jesus Christ (John 6:53-56) in some spiritual manner (John 6:63), or they may suffer the consequences, even in the here and now (1 Corinthians 11:30).
And yet, few, even few Catholics, actually believe that Jesus is really present, body, blood, soul and divinity, in the Eucharist. Which is prayed for by a consecrated priest.