Baby nutrition

Hi mummies.. Need some advise here. My 13 month old baby is quite small size since birth and has been on the lower percentile. She was full term but just small size. She takes 3 solid meals per day and is on full breastmilk. Eating wise not a very good eater. She gets full fast and does not consume much too. Otherwise she is healthy, active and hitting milestones well. I am thinking of transitioning from breastmilk to fresh cow's milk during the day for my baby and continue to latch at night. Which will be better nutrition wise and for her to gain some weight? Fresh full cream cow's milk or UHT milk? My daughter completely rejects formula. So that isnt in the option. Thanks in advance for the advice :) #1stimemom #firstbaby #advicepls