Hates tummy time

Maranda

My son is 7 months and three weeks . I do tummy time multiple times a day and the longest he will stay is like five minutes. He is finally starting to somewhat bring his knees under him but I feel like he is behind and I have been trying everything to encourage him to move around. He can roll from him belly to back and just choices not to and screams and screams till I give a little assistances. Any advice ?