Period back already??

Currently 10 weeks postpartum with my third baby and exclusively breastfeeding. No change in her sleeping through the night or major feeding changes but my period started yesterday and am now noticing a big drop in my milk supply. My older two were also exclusively breastfed until 12 months or beyond and my periods returned around 9 months postpartum. Has this happened to anyone else?? Getting concerned I won’t be able to nurse by baby due to the low milk supply.