Periods and Breastfeeding

Doricia

My baby is only two months old. I have breastfed him since birth. He was born in May and I have had sex at the end of June and missed my July period. When me and my boyfriend did it, it was only the tip for literally two minutes because it was to much pain after having my baby. There was no pre cum to my knowledge and he never cam. So should I be concerned about being pregnant? Is it normal to miss a period when breastfeeding?