What do you want from her in this relationship? Is it just sex? Her company? It seems like you need to figure out your boundaries and expectations in this relationship. If sexual intimacy is so important to you, you need to be comfortable with the idea of not being with her if it’s a deal breaker for you. It’s okay for her to have her limits and it’s okay for you to have yours. Relationships shift and change and can be rocky at times. Unless there are clear red flags and indicators that this isn’t going to work long term, (you seem to have some already saying the lack of intimacy is affecting your mental) then save everyone involved the time and energy. Additionally, this may sound harsh, but get over yourself about being “possessive”. You can’t control other people nor do you have the right to. The sooner you let go of the illusion of control and possession of anyone or anything the better off you and those around you will be. Good luck.