I think having a heavier period after is kinda normal. Mine use to be anywhere from 6 to 8 days, I've only had one pp and it lasted 9 days but was way heavier bleeding then what i use to get and I honestly thought it was going to last a week and a half
When I got mine back it was 8 days gone 2 weeks then 8 more days and regulated after that. Takes some time to get regular again
I believe it’s your body trying to regulate…I got my 1st period like 4 months postpartum and it was heavier than before and has been heavier since so far but mines is only about 5 days I just think our bodies changes after having a baby