Could I be pregnant?? Help!!

On the 17th of March me and my boyfriend had unprotected sex, he pulled out a good few minutes before he came, as I finished him off. However I am aware of pre cum and all that, but the likely hood is pretty low right? My period was due on the 29th and I still haven’t got it. I’ve only had my period for about 2 years so I’m not exactly regular, but my average cycle length is 35 days, however I literally range from 20-69 days 😂 I’m under a lot stress right now as I have exams coming up soon. However it is playing on my mind that I could be pregnant. I cant go an buy a test as I’m only 15. I’ve had tender boobs for a few days now, and My appetite has gotten really bad, I’m not eating no where near as much as normal. I’m probably just being paranoid. But any help is appreciated!!