GF(20F) doesn’t feel like having sex, Help.

*Before I start I would like to clarify, I’m not trying to pressure her, I’ve become self conscious over this whole thing.

Me (26M) and my GF(20F) used to have great sex all the time. We’ve been dating for 3 years! Recently about 6 months ago, we started having sex a lot less often. When I brought it up it turned into a fight, I said I wouldn’t bring it up again. She said she hasn’t been in the mood for it. Which I understand, everyone goes through phases like that. What’s bothering me, is the last couple times we did have sex, she made it obvious she wasn’t enjoying it (not a sound, no movement, etc), that left me feeling very self conscious with everything. I brought it up when we got into again about not having sex and that was completely ignored. It really did some serious damage to my self esteem, making me not want to initiate anymore. I’m already not a super confident guy, so it knocked me down a few more pegs. Yesterday when I was at her house, her vibrator fell out from her bed which was funny. But she mentioned how often she uses it and subtle things like that. That made me start thinking about all of this, does she not want me anymore? Am I suddenly not good enough? Does she just not feel like having sex with me? I find myself thinking that she’s with me just as a “safe option” and doesn’t want to hurt me and tell me she’s done with me, but that could just be my negative self confidence talking. I can’t bring this up again because she made it specifically clear to me not to bring this up to her because it makes her feel like shit that she doesn’t feel like having sex. But it’s something that is literally driving me crazy at points. I want to be intimate with my GF.

I absolutely adore this girl, we have plans on moving in-together soon, and we get along amazing. It’s just very difficult for me personally to go with no sex for weeks, and then when we finally do have sex it’s clearly not enjoyable for her. Im not sure what to do.

Please don’t just comment dump her, I came into this group to get some actual feedback for once.