Delayed development 2.5 month old?

Hey ladies, my 2.5 month old son is still struggling to lift his head during tummy time. He does lift it but only for a few seconds and then its down. We try to help him by putting his arms in a triangle under him but he just immediately starfishes back out. He also isnt pushing up on his arms just yet. He has no trouble supporting his own head when we hold him. We just have to support it when bending over when we hold him. And he does hold it up when we put him in a seated position. He just struggles during tummy time. weve also noticed hes not reaching for toys above his head at all just yet. It almost seems as if hes kinda delayed/lacking upper body strength no matter how much we do tummy time or help him improve it. Would you mention this to the pediatrician? Should we be seeing an OT yet or is this still normal. Sorry FTM here. I just see one of my friends babies who was born 2 days before my son lifting her head during tummy time and holding it up and even rolling over but my son is still struggling. Cant help but feel like something isnt right here.