Is it normal that i'm a straight female, but sometimes get aroused by women?

So, I'm a female teenager, attracted to males, but today I was watching a video by Music Video Sins, where they "make fun" of music videos, and one of the music videos was Crazy In Love, and there was a close up shot of the singer's (Beyonce's) buttocks, and she was putting her hand on it and stuff, and I became aroused. Also, when other females wear tight clothing and low-cut shirts and stuff, I kind of get a nervous feeling in my stomach.

I do have social anxiety, and am consequently rather lonely, and I also have mild H-OCD, if that has anything to do with it. Thank you for your honest input.