hey!

I am not an expert but thought i would jump in here with my opinion lol
( this is all stuff that i was told byt he way lol)

Tummy Time is needed by all babies but it doesnt have to be huge amounts but they need the tummy time to develop muscles and also to avoid getting flat spots on their heads.
i had a hard time with my DS2 cause he wore a hip brace for the first 12 weeks and couldnt lay flat on his tummy so we used to lay him over our arms just so he still got that time to build his neck/back muscles.

I am hoping someone else will pop in and give you a more deffinate answer but i am pretty sure tummy time is pretty important and you should persist with it... ( i know that sounds really insensitive cause i know how hard it is, and it would be so much easier to just give up on the idea but i honestly think it is important!!)

i hope some one has some great idea that fixes it for you hun!