If I'm not hearing from God, I am truly lost in life.
I came to this place many years ago. Realized the vast majority of what I though was Gods personal messages to me was not from God but from a spirit of false prophesy. It crushed me but it wasnt really really hard. There are a lot harder things that one could go through. And it really shouldnt be hard once you realize that it isnt that God wont speak to you. Its just that you have to learn how to recognize whats from Him better.
I have been promised (metaphorically) the sun, moon, and stars and if the promise fails it puts doubt on if I've ever heard God in the first place.
Be careful here. You have many many many great and exceeding precious promises in Gods word. These are like unmovable mountains in a raging sea. You can rely on them and know that they are 100 percent true. You can build your whole life on them without one worry that they will ever fail.
Specifically how would know if it's Satan mimicking God's voice?
This is not easy to answer. I have been trying to learn this for years and I still dont know whats from God and whats not (as far as subjective personal words from God are concerned). You really do need to be filled with the Spirit and given the gifts of prophesy to really be able to operate well in this arena I think. Otherwise 9 out of every 10 words you get are fake lies from Satan and its just to difficult to pick out what the real one is.
A rule of thumb I use though is this. God will speak to me primarily through putting me in situations where it is obvious what I should do. He wont tell me what to do (aside from the whole bible) He will just put me in situations where my own reason will plainly see the right path to take. And its something that He gives me joy in. If it fills you with fear or panic like I have to do this now or else then its often not from God I would say. He is patient.
As far as the words on peoples shirts and stuff like that sometimes God will give me an encouragement through stuff like that but apart from that I think 95 percent of that kind of stuff is from Satan.
But again the only thing you can rely on is the scripture. And its not enough to just read through it a few times. You need to know the word like the back of your hand. Meditate on it day and night. If you open it and when you read you dont understand half of what it says you really really need to know it better.
Satan will speak to you through the scriptures, through pastors, through the people you look up to most and he will use the good words they say in a twisted way at the wrong times to get you to do foolish things. And the only way to protect yourself is to be like Jesus in the wilderness. See the twisted truth and respond with the scripture that corrects the twist.
And another thing is you dont need to "discern Gods direction" in order to follow Him. If you just read the word and do it and forget about "leading" entirely you will do just fine. God will be with you in that path. This is what I am trying to do honestly. All that special revaluation stuff is legitimate. But it is more for those who really want to operate in a prophetic ministry in some capacity. And thats a hard path. I would say dont go down that road unless you literally cannot resist it. But realize its a hard life. At least it seems that way to me. I may be wrong.
God help you man.