Idk what’s happening😢

I’m going to start off by saying that I have always been a major worrier and over thinker. So me and my bf have been dating for 4 years now, he’s my bestfriend I love him so much. I can’t see myself without him anytime soon or at all really I don’t want to be, he makes me so happy but about a month ago I was sitting on the couch and randomly had the thought “what if we’re not really in love and just obsessed with eachother”, I worried about that for about 3 days and then another thought came and it was “what if your just forcing yourself to be with him” and now for the past couple weeks this last thought is the one that’s really killing me “what if im falling out of love with him” it’s destroying me I hate these thoughts especially the one about me not loving him anymore, about 2 weeks ago since these thoughts werI getting to me badly I went to my family doctor and she said it sounds like I have generalized anxiety disorder and she said I should definitely try CBT and talk to a therapist I was fine for a few days after that the thoughts were there but i could smile but not there back and I’m not hungry all I want to do is cry, I love him so freaking much this scares the shit out of me, I’ve talked to him and told him everything jinf and he’s so supportive and told me that “we’ll get through this together” “I’m not going anywhere I know you love me”😢 I feel crazy and like a terrible girlfriend when I’m with him or on the phone thing are usually normal and I don’t think about them as much if it all but occasionally I’ll start to think about how I feel and analyze my feelings it sucks😔I know I love him I wouldn’t be here if I didn’t bc were in a LDR and I only get to see him every 2 weeks he lives an hour away and Ik that’s not that far but it still hurts.. Has this happened to anyone? What did u do to help? Anyone please