Doubts on starting back breastfeeding

I stopped breastfeeding for about 1 month+ ago & currently giving my child formula milk (i tried to breastfeed him for 4 days by pumping after giving birth to him) but my baby boy keeps on hitting his head against my chest & grasps my breast when i'm not fully dressed as if he wants me to breastfeed him coz i still have some milk in my body however i'm having doubts right now if i should as it's been awhile i stopped coz i can't get him to latch as my nipple is sunken in also i don't know what i can consume if i'm breastfeeding coz i don't want eat to affect him making my son fall ill so i'm really feeling a lot of doubt & guilt whenever he cries & does as described 😔❤️‍🩹❤️👶🏻#advicepls