loosing feelings..

I've been with my amazing boyfriend for 6 months. He's honestly the best guy. He treats me amazing and definitely the kinda guy I would want to marry. We started out as friends then we kinda started hooking up and getting Together. He's such a good guy but for some reason I feel like I'm loosing feelings for him. Like I know I love him and I want to be super in love with him but I just feel like I can't be. I have talked about it with him and we just decided to work it out because I've been on birth control for 3 months and I feel maybe that's why it's making me loose feelings. I use to feel super in love with him but the past month or so I don't feel the same...I just stopped taking birth control because it's bad for me. So how long should I stick it out to see if it was the birth control or actually if I am loosing feelings for him ???