Itchy vagina!!!!!

I’m 17 and my boyfriend and I have sex regularly and without a condom (because I’m on the birth control pill). I have only had sex with him in my life and he had one other partner in the past. Since I am sexually active with him (for about 4 months) I have had two infections on my vagina: I get very very itchy down there. On the first infection I applied a medical cream that actually took care of it. Three weeks later the same symptoms started showing up again and I applied right away the same cream and it calmed down again. Two months later I am starting to feel really itchy again and we had sex yesterday (and it actually hurt because I’m am also very tight and we didn’t use lube).

Ps we always clean our private parts before having sex (although I think he forgot to do it two days ago)

Is this normal?

Does anyone know what triggers this itch and can I do to solve it?