Heavy Bleeding on Kariva Birth Control: What to Know

Question
hello,
i just started taking kariva birth control pills this month.  i took my 3rd sugar pill and got my period this morning.  my periods, before i took the BC pill, were very regular and never too heavy and cramping was never an issue.  but when i got my period on the sugar pills i got it very heavy and i noticed a clot that was bigger than expected.  i know the pill causes blod clots so im guessing that could be fine, but i heard it could be a miscarriage.  that makes me nervous but i doubt it.  when i first took the pill i did the DAY 1 start and took it within the first 24hrs of my period.  i was told they worked right away.  i waited, however, for 7 days before my boyfriend and i didnt use a condom, (both are std-free, got checked). i was told however, i was not protected and got nervous and took plan b  4 days after sex.  could i still be pregant even though i got my period?  i took a pregnancy test and it came out negative and plus i got my period.  could the heavy period and cramping be due to the plab b or the fact that the pill is new to me?  thanks for your help

Answer
Hi Laur,
I wouldn't be worried.  Since your period came when expected it's very unlikely that you're pregnant.  I suspect the heavy period is because it's your first month on the pill.  Most likely your future periods will be lighter.  Generally it's recommended to wait 7 days from when you first start the pill, and you did that.  I'd keep taking the pill and expect everything to get normal with time.