I’m so scared :(

So I’m on birth control, have been for ages, always use condoms tho. The other night my boyfriend and I had sex but didn’t use a condom. Since I’ve had light brown discharge, almost water like and I’m scared I’m pregnant (this is a massive fear for me anyway) as google just keeps saying implantation bleeding! I finished my last withdrawal bleed nearly 2 weeks ago, not due for another withdrawal bleed (week off the pill) for another week and a half. It can’t be ovulation bleeding because I’m on the pill. I just don’t know what it is and it’s driving me crazy to the point I am CONSTANTLY going to the loo to check. The sex we had was not really rough but was deep I guess? He did cum inside me. No other pregnancy symptoms. Please help:(