Phonology is killing me

I have a midterm tomorrow, and I'm legitimately worried about it. The worst part? It's in a linguistics class! Phonology is messing me up. I've never had this much trouble with anything linguistics-related before. Could my problem be that I don't like it as much? Don't get me wrong, it's pretty cool, and I do think about a lot of phonological things now and then, but it's not my calling, and I know that for an absolute certainty. I would read my semantics book for fun, even though our professor was so good that we didn't strictly have to, because I love semantics so much, and it was completely fascinating (not to mention well written). But my phonology book, professional though it is, doesn't have the same kind of draw, and I think that's fairly indicative of where my preferences lie. So maybe it's my own fault for not being interested enough. But no, I don't think so. I've done extremely well in classes that I wasn't interested in. Well, okay, that's a tricky thing to say, because I don't think there's been a class ever that I haven't liked at least some. Even my 9th grade biology class had some interesting bits, and life sciences are so not my thing. Learning is learning no matter what, and I'm just happy to take anything I can (oh, except PE class; that's the one exception). There have been classes that I've liked less than phonology (anthropology comes to mind), and I was fine there. And honestly, I think phonetics was a little less interesting than this class, and I did okay in there. I mean yeah, I ended up with an A- in there, but in the grand scheme of things, that's not too bad (and part of it was because I forgot to turn in half of my preliminary report). So I just don't know what I do. And I feel bad, because both the TA and the professor are so good! I feel like I'm letting them down. I want to be better, I really do, and I try, but something just doesn't seem to be clicking. I understand conceptually what everything means, but when I go to do the problem, I hit a wall. Do you know, on the last homework, I could only figure out one phonological rule, and I worked on it for about three hours! I feel so incompetent, and it's so terrible. I'm not supposed to be incompetent at linguistics! Yeah, of course I have struggles, I'm not perfect, and sometimes I'm frustrated or need help or mess up on things. But in the end, I love it, and I'm good at it, and it's my rightful passion. Until now. Why is it that I can't even do these simple problem sets? How am I worse than everyone else in the class? Are they floundering too, or are they all part of some exclusive club of future phonologists who know exactly how to apply rules and order them so they work? I'm really very distressed about this. The persnickety perfectionist part of me says that I should change my major to anthropology, or drop out of school to become a trophy wife, since I obviously can't succeed at anything once the going gets tough. But the stubborn punk-ass part of me wants to keep going and bulldoze my way through the wall until I get it. And then of course the nerd side just wants to learn, no matter what the consequences are (my nerd side is very impractical and myopic). So I'm probably going to keep going. What else is there to do? But oh, I'm so scared! I feel sick, and I'm putting off studying for tomorrow, because I can't concentrate. What can I do? I want to do well, but I don't know how. It's no good having a powerful brain if you can't use it, now is it? I have to do something about this. Of course I'll study and go to office hours tomorrow, but beyond that? Where can I go from here? I need help.