Started period during sex, but nothing afterwards....

Ari

So I’m supposed to get my period tomorrow and this morning my boyfriend and I were having sex and I noticed when we were done that here was some blood on the condom. So I thought “alright I got my period today” but I haven’t bled at all the rest of the day. That happened about 8 hours ago. No blood at all, has this happened to anyone else right before their period?