Please help I think I might be pregnant

So about a month ago I had sex with my boyfriend for the first ( used a condom and he didn’t finish inside of me) anyway so I’m 15 and my parents always wanted me to tell them before I did anything but it was a spontaneous thing so I talked to my after and asked if I could go on the pill ( my mum thinking I wanted to have sex in like a few months) and all was good till I realised I have missed my period by almost a month ( which isn’t that weird as I’ve always have irregular periods) but I’ve felt really sick lately and I have this weird feeling in my gut that I’m pregnant and my doctors appointment is tomorrow and I was always gonna just say I hadn’t have sex but what if I’m pregnant???? Just wondering what are the chances that I would actually be pregnant ????