Bek just going through the same thing myself.. I just put olivia on her tummy.. I have an angelcare monitor though.. I put her on her back or side when she first goes down then her tummy if she doesn't settle at the next feed..

If she is getting used to her tummy during the day then she might expect it at night kwim? If you really aren't keen on the night tummy buso.. Maybe start training her to sleep in a different position during the day...

If you keep her awake during the day you will end up with one very overtired and grump baby who won't sleep anyways.. How do you feel about her sleeping on your chest on her tummy at night? Even if it just so you both get some sleep to be able to deal with the situation once you are both well rested?

Good Luck.. I hope she starts sleeping soon