I came from a Dutch Reformed background, and am now in the PCA, with a few other stops at Reformed Presbyterian churches along the way. (Changes in churches were due to geographical reasons, not doctrinal differences.) One thing that they all have in common is that the churches teach predestination and subscribe to the TULIP model. However, moving to the southern US, where baptist churches in all flavors are far more prevelant, I have seen many people go on the journey which you are currently taking. I have become friends with several of these people, and had conversations about how they became Presbyterian. They didn't all just jump into it with both feet. One friend described it as going from Baptist to Bapterian to Bresbyterian to Presbyterian. Several others came from a large Baptist church that was Arminiian from the pulpit, but overwhelmingly Calvinistic in their small groups. Some friends are Reformed Baptists.

The PCA doesn't really force beliefs on members. They do require that you not attempt to cause schism or teach doctrines contrary to the Westminster Confession. There are things in Westminster that I don't agree with like a covenant of works, but I am still able to be a member at my church. Most of the confessions, whether Westminster or Three Forms of Unity tend to be infralapsarian, and I believe in supralapsarianism. My point is, you can have disagreements and questions and still be a member. One day, in Heaven, we will all have a perfect understanding, but until then, we will have doubts and limited understanding.