I’m bi but might be lesbian??

I need some serious help I am 18 and have been out as bi for 5 years maybe 7. For the past two years every other month I go down this spiral of thinking i might be lesbian. I can’t tell if I am into men or like the idea of men. Sometimes I when I am intimate with a man I wish he was a woman and everytime I’m in a relationship with a man I can’t stop thinking abt what if I was dating a man. I have dated women before but that was in middle school I’ve always dated mostly men so it feels like I’m going crazy but I can’t tell please someone give me advice🙏🏽😭