Insecurity

Hey guys, I just wanted to ask you something... So I am very stressed lately because of school and work and I get really emotional when I'm stressed, but recently, I get these kind of waves of insecurity coming over me, I don't know how to describe it... for example my boyfriend and I are really happy together, we've just seen each other today and everything's fine, we love each other. But then when I get home there comes this feeling that I'm not good enough, that he'll replace me... Same with school, I usually get good grades, same today which I was really happy about, but suddenly this thought pops up in my head that I'm not good enough and I won't be able to graduate... Why??

I hope what I am saying makes sense? I just don't know how to deal with these negative thoughts you know? Usually I am a really happy girl but these thoughts being there for no reason really bother me 🙄