Pregnant?

I had sex about 4 days ago, on Saturday. Me and my boyfriend used the pull out method - although you think he would want to use a condom because he already has a kid (he's 17 im 15) - anyways he pulled out and cum immediately was on my stomach. It didn't cross my mind until now but I started thinking maybe some landed inside me. I checked my period app and I was ovulating when we had sex. Since yesterday I've been expirencing  cramps, stomach pains, heartburn, wanting to throw up, headaches , I don't know what it could be. Any advice is helpful .