Period and pregnant

I would really like to know if and how it’s possible to still have a period while pregnant... I know that implantation bleeding and breakthrough bleeding can occur but a full-on, heavy period?

For those of you who experienced “periods” during the first few months of your pregnancy: did you actually bleed enough to fill a tampon? And how long did you bleed for each time?

Is it really possible to have a 5-7 day period with enough blood to fill a pad or tampon (at least once)?