Hi mama! Totally normal yan, especially kung exclusive breastfeeding ka pa, maraming moms sa circle ko ang same experience, wala period for 8-10 months or even longer dahil sa lactational amenorrhea (fancy term for balik period delay from breastfeeding). But since you're 6 months in na and want peace of mind, I'd really suggest checking with your OB-GYN especially if may unusual symptoms, kasi siguro naman mas okay if doctor mo na lang i-monitor, di ba?