welcome to HCM!
It's hard to say exactly when your periods will start again. The timing is different for every mum, and it depends on your body, as well as how you are feeding your baby.
If you're breastfeeding
, this will help to delay the return of your periods,it can be up to a year before you have a period. It's known as the lactational amenorrhea
If you're lucky enough to have a baby who sleeps through the night from an early age OR if you're supplementing with formula,your periods will probably return sooner within three months to eight months.
, it is important to remember that you can still get pregnant even though your periods have not yet returned. This is because a woman ovulates about two weeks before she has her period.As you had a negative pregnancy test so there is nothing to worry.
hope this will help