My boyfriend and I had unprotected sex a day before I was highy fertilizing he came inside me. Could I be pregnant?

Well it's basically 50/50.
You either ARE or you're NOT.

You'll have to wait for you next cycle before you can take a test..

Yes, of course. Why would you think not?
Percentage is not meaningful, because it's the world of women as a whole. Let's say it was something like 17% for one time sex mid cycle, at your age, no medical problems, and no birth control. What good is that, if you are in the 17%? You are still 100% pregnant in that 17% group. Countless women get pregnant the very first time they have sex.

Since it was the right time and no protection, your odds are geater than if there was protection.