How to deal with anxiety in a relationship?

I’ve been with my boyfriend almost a year and I still can’t get over my anxiety. We have had fights here and there but never anything serious like cheating or anything else considered bad lol. I love him so much and I know that he loves me just as much or even more, but i cannot get past my anxiety and overthinking. We go to different schools (he’s still in high school and i go to a community college) and that causes most of my overthinking. I constantly think that he’s with someone else or doing something he shouldn’t be. If he doesn’t reply to me fast enough I start panicking that he’s found someone else and he’s going to leave me. None of this has ever happened but my mind makes me think this way and it’s driving me crazy. It causes so many problems in our relationship because he will not reply for 5 mins during lunch and i know he’s at lunch so he should be texting me so i get scared and then when he does reply he tells me what he was doing and i don’t believe it and i get annoyed. It’s driving me crazy!!! I have been thinking about going to a therapist for my anxieties but to me it sounds silly for me to spend a bunch of money just for me to sound like a crazy girlfriend. I really want to be able to stop thinking like this because it’s hurting me mentally and hurting my relationship :(

Has anyone dealt with anything like this? And should I go to a therapist?