GF & I Barely have sex and don’t know how to approach her

My GF (22F) and myself (22M) barely have any sex, i constantly need to initiate it. We have been together for 5 years and known each other since the beginning of High School, we have been through alot of shit together and the sex was great in the beginning, almost every day of not twice a day. I dont know when things changed by her libido just keeps going down and down. I have ADHD and bipolar plus a few other things, this makes my libido super high for some reason and im almost always horny. We maybe have sex maybe 3-5 in a month, she sometimes just have sex (i need to initiate it without being “pushy” and i dont even know how to bring it up with her anymore, we both just get depressed as i feel my libido to high and feel like shit that mine is so high, she again feels shit that her linido is so low.

Honestly i dont know what to do, yes there is probably alot more context to this.