A little help

Hey guys! I hope everyone is having a good day! I need some clarity on a situation really quick. Recently I came to the realization I have never spent anytime being a young adult outside my relationship. I got together with my man 2 months after I turned 18, got engaged a year later at 19 and now I’m feeling like I need some alone time by myself. I need some time to find myself and discover who I am by myself as a young adult. I’m nearing on 21 now and have barely spent any time with anyone outside of my relationship. I don’t go many places by myself, I don’t hangout with friends often, I’ve never even been to a concert. I feel like I’m in an unhealthy relationship with myself, and I don’t think I can be in a healthy one with my fiancé if I can’t be in one with myself. Does this sound selfish at all? I’m so scared to talk to him about it because i have a feeling he will just want to break up if I tell him I want a break. He has bad anxiety so he’s always asking me if something is wrong and I feel like I’ve been lying to him as well as myself as I’ve just made this realization this weekend while spending time at my sisters and being around a bunch of new people. I’m hoping someone can give me any spot of advice on what to do. Thank you everyone!