I Had Sex With My Boyfriend And He Used The

I had sex with my boyfriend and he used the withdrawal method where he pulled out before he ejaculated. This happened a week ago and my belly is bloated now and I haven't come on my period and I was due to start two days ago. I'm worried I'm pregnant but I'm too scared to go to a doctor or get a test as I am underage. I know underage sex is illegal but I'm really concerned about this situation! Please help, I'm worried and have no idea what to do.