Aunt flo question

For reasons: i breastfeed 4-5 times a day (or pump & get 4-6oz per session) and give baby formula after breastfeeding / whenever he wants or will take it (he needs to gain weight per pediatrician)

Been doing this for like 4 weeks now. 12weeks post partum and still no period. I thought the more you supplement the more likely your period would return?

Anyone know if its normal to not get it even when i don’t breastfeed thar much?