Approaching 4 months baby boy | Severely underweight | Pure breastfeed

Hello mommies, My first born baby boy is weighing 4.3kg. Going 4 months next week. Purely breastfeeding. Okay yung latching niya. Siguru my suspect is meron syang lip tie? (see google photo below). Di pa din kami nakapacheck up sa pedia. Or low fat content yung breastmilk ko? Need ba ko x2 yung food intake ko? I'm taking malunggay capsule and calciumade. What to do mommies? First-time mom here Gusto ko talaga exclusive breastfeeding c lo Dapat ba ako magworry sa weight nya? Or normal lang for exclusive breastfeeding babies #BreastfebBabies #breastfedbabies