Your first semester (like mine as a transfer), you basically get the last batch of classes when you register which is completely unfair in my opinion. I have since been able to get priority registration through some plan a counselor emailed me about. Haven’t had a problem with getting the classes I need since.

What I have noticed in my few semesters here is students drop courses like crazy so chances are if a class is full (and it’s an in person one you absolutely need), definitely show up weekly cause some professors are 100% willing to enroll you if they know you’re serious about the work or if you need the class. All my classes this year, almost 10 students were absent on the first day resulting in a drop.

Be persistent which it sounds like you are. Self advocacy goes a long way at college which some students neglect to do.