On my period and prego ?

hello again,
well it's been a few months since i've had a pregnancy issue.

okay so here it goes:
we been having sex,and i started my period...i usually go through a about a half or three quaters of a playtex super plus box of tampond the day i started my period i had really bad cramps! i mean really bad i was in tears and everything. and for im on my third day this everyday theres been an extreme amound of brown dishcharge or something brown,today i woke up (it's my third day) and there was not verry much blood,i know i was sleeping but i was put a tampon in before i was even getting ready to go to bed. anyway, today i've only used about two tampons and usually my third day is my heaviest...
my period started a few days late i was suppsosed to start on 5-28-10 and started 5-30-10
and my period before that i started on 5-1-10
could i be pregnant or had a miscarriage or what?
plz help!