What Causes Heavy Periods After Delivery?

since giving birth almost 2 years ago, my periods have been heavier and slightly more painful (as apposed to no pain and quite light periods before i gave birth) i had a smear test 6weeks after birth and it came back with nothing to worry about. recently i have been noticing that ive been gettin slight aches even when not on or due a period. a couple of weeks ago i noticed a "show-like" discharge like just before you have a baby (im not pregnant). this was two weeks after my period and ive had nothing since. i was wondering if its possible to bleed like this during ovulation?