He wasn't wearing a condom and I'm not on the pill - am I stressing myself for nothing

If you had unprotected sex you could be pregnant. Even if your boyfriend didn't ejaculate inside you, semen still leaks out before the final ejaculation so you can still get pregnant. If you are not pregnant it you could go and talk to your doctor about long acting reversible contraception (LARC) which is safer than condoms and the pill. Having said that, you would not get pregnancy symptoms the day after, even if fertilisation has happened. These don't usually start until a few weeks later. You will have to wait until 3 weeks after unprotected sex, or a few days after a missed period before you can do a pregnancy test. If you have a possible accident there is the option of emergency contraception from a pharmacy or young persons' clinic for support around unprotected sex.