What Causes Heavy Vaginal Bleeding After A Miscarriage?

Hi

I had a miscarriage 8 weeks ago and haven't had m period since. I've done pregnancy tests but the are negative.
I'm going on holiday in 1 week. Is there anything I can do start my period or postpone it til we come back? I've also heard that the 1st period after a miscarriage is heavier and crampier than normal....is this true?

Thanks


Frankie