implantation bleeding

my boyfriend and i are trying to concieve(it will be the first child for both of us) about a week and 2 days ago we had sex multiple times. about 2 days ago i started to have heavy bleeding so we were both very disappointed then this morning the bleeding stopped. my boyfriend read online that heavy implantation bleeding is actually more common than you would think and could even be a sign of twins! Then a few hours ago i began bleeding again and were both very concerned. Were just wondering if anyone else has experienced this or could offer any advice we would very much appreciate it!