Talk to Pediatrician on Baby Not Feeding

Hi, I have twins babies, they deliver premature at 34 weeks pregnant due to my water broke ,, now they are 8.5 month ... but as dr. Said they consider them 7 month now as because early birth ... so my question is ... they have so much feeding problem my twin 2 baby girl she refused to drink milk when she was only 2 months then now after 4 month she wants drink normally in this 4 months i feed her forcefully ... nd now almost 2 month going my twin 1 baby boy he refused to drink milk ... but after birth or till sep 6 he was drinking very well but dont know what happened i also see dr. But dr. Said you give him after 4 to 5 hours then he will drink or give when he cry for milk but 4 to 5 hours later he drink only 50ml to 80ml in just 5 mint ... after this he just keep nipple in his mouth nd dont suck .. even i change his formula milk from NAN to ENFAMIL ... but still not working ... i dont want to go hospital due to covid situation .. because they are small baby ... can you help me how i