Questionable bleeding.. HELP!

Hi there. I'm new at this and don't exactly know how to post this, I'm a 20 year old who is fairly healthy and I haven't been on birth control for about 8 months now, my husband and I had sex earlier in the day and I bled right after but after I wiped there was no more blood. My period doesn't start for 7 days but we use the pull out method.. he smokes pot so I know his sperm count is probably low, any ideas? Help please!!!