Could I be pregnant?

So my boyfriend and I were fooling around 2 days ago, there was no sex but he was rubbing  the tip of his penis on my clit until I had an orgasm, and he didn't cum and I gave him head after and we were done doing stuff. he said there might've been pre-cum but he wasn't close to my hole at all. I'm supposed to be starting my period tomorrow but I'm just kind of worried that there might be a possibility that I could be pregnant. I don't feel any different, the only thing I noticed that I have thick white discharge but I think that's normal because I'm about to start my period. could someone please let me know the chances I could be pregnant? I'm worried but I'm trying not to stress too hard.