Even though He made the sacrifice He made, I sort of think that I didn't ask Him to do that personally,
None of us did - none of us would be capable of asking such a thing.
And we'd have no right to advise God anyway.
therefore I don't feel it is my duty/responsibility/whatever people may call it to serve Him
Some of us call it a privilege to serve - and we do it from love, not obligation.
as I didn't get a choice about whether I exist or not, and it seems unfair frankly.
None of us get a choice in whether or not we are born and therefore exist. What's unfair?
Chances are if I somehow knew before my life began that serving God or going to Hell were my only options, I'd likely just opt to have never existed in the first place.
They aren't your only options.
God doesn't stand over us with a big stick saying, "serve me or you'll go to hell". I'm sorry if anyone has given you that impression, but it's false.
God says, "I made you in my own image. I love you and want you to be my child, and this will happen if you believe in and accept Jesus who gave his life so that you could know me. If you are in Christ you will have every spiritual blessing that there is - hope, peace, security, assurance etc etc, Ephesians 1:3. There is no condemnation for those who are in Christ, Romans 8:1 and perfect love drives out all fear, 1 John 4:18."
That's what God wants for us - it is his free gift, Romans 6:23. If anyone is told, or knows, about this free gift and wants to accept it - they have eternal life and become a child of God. If people are told about this unconditional love and free gift of God but choose to reject it, and continue to reject it for the rest of their lives; if they say "I don't want to live with God", then when they die, that is exactly what happens. They don't get to live with God.
Serving God, keeping rules, going to church or anything else that you can think of does not impress God nor earn his love. No one can earn his love - he, in his mercy, chooses to show it to us.
I'd likely just opt to have never existed in the first place.
You'd rather miss out on life because you are under the mistaken impression that it means 60 odd years of service/slavery to God?
Jesus said, "the thief comes to kill and destroy; I have come that they should have life, life in all its fulness." John 10:10.
God forced me to exist and now He expects me to be His servant or burn in Hell when I die,
No, he doesn't.
You either have the wrong idea about God or you are a victim of bad theology.
Or you're depressed.
it's almost like a dictatorship to me.
If that was what God did and what he was like, maybe - but it's not.