If we're free, then how is God truly sovereign over all?
Sovereign means that GOD is the One Who does what He pleases. It also means that God is "in control" but not necessarily "controlling" us like puppets. IOW, you are a little creator in God's universe... but God is in control of your surrounding circumstances...and God as Owner of the universe has the absolute right to execute a sanctum flexibus of all of human history interacting with all human freewill.
If God is sovereign over my choices, then how am I free?
Freewill is NOT perfectly/exactly synonymous with "freedom." Freewill just means the ability to choose freely between two or more options. This doesn't mean that the options, however, aren't sometimes VERY limited based on circumstances of coercion. A person who is in bondage under captivity or slavery still has libertarian freewill... because freewill is "self-generated." They may choose between a lessor of two evils...but when you are discussing freewill you are discussing an "internal ability" and NOT having to do with external circumstances.
God allows your choices...God can remove the restraint of evil...God can allow you to be tempted by unclean deceiving spirits, etc. God can harden your heart by allowing you to harden your own heart through a series of your own bad choices and agenda. People often do not understand this process and wrongfully think "hardening your heart" means a removal of freewill. It doesn't. Scripture said that Pharaoh hardened his own heart. The concision of God hardening someone's heart does not explain the process...but we can see the patterns in scripture of how God can remove His restraint on evil and allow someone to engage in a series of their own bad choices which hardens their own heart.
God interacts with all human freewill in a synergism of all circumstances including the natural order.
This is important to understand... in order to understand the compatiblist's argument and theology.
there is absolutely NO contradiction between God's omniscience and human freewill...as William of Ockham already explained in the 14th Century that God's omniscience and foresight is dependent upon what we will choose.
Also, if you wrongfully isolate on the end result...you will be ignoring the freewill decisions which take you to such end result. University profs wrongfully do this all the time.
If God isn't sovereign over my choices, then how is he really sovereign over all?
Your choices/decisions are self-generated when you have valid options to freely choose between them.
God's sovereignty is based on GOD doing what He pleases and being "in control." There are many things
which God can indeed control and still allow you to have freewill within a set of circumstances which God allowed or controlled many of the variables (the natural order, for instance). It doesn't mean that God isn't sovereign if He creates little creators in His universe. You are still accountable on judgement day.
For either view being true the implications are less then palatable
several questions like these (such as Divine freewill being compatible with omniscience) have already been resolved... but people are not generally familiar with the answers, however. (unless they are a Christian philosopher or a systematic theologian). God doing what He pleases (sovereignty) and being IN CONTROL is not diametrically opposed to us self-generating our ability to freely choose between options. Freewill is a necessity for love, genuine relationship, obedience and worship. God will judge freewill decisions someday and display His justice in eternity. Without freewill there is really no such thing as moral evil (sin). (or love, true worship, true obedience, or logical rewards).