Not In The Mood...😶

I don't know what it is but for the past 6 months I really haven't felt like having sex or anything. I thought it was just stress and stuff for a while but now it's really getting to me because I'm not stressed or anything right now. My boyfriend loves me and says he doesn't care but I know he wants to be intimate (been together about a year). Sometimes I'll just have sex with him but it's just to please him and make him happy. It feels good and all but I don't know. I just don't get horny like I used to (I'm 20 by the way). This ever happen to anyone? Would a doctor know why my sex drive is so so low? Would switching birth controls make that much of a difference..?