chezzies u r aloud to sleep on your front, theres no reason other than being uncomfortable why you cant, lauren i occasionally sleep on my front and i love it 
i copy and pasted this of the harley medical group page xx
Breast Enlargement: Can you still lie on your front?
Ladies can certainly lie on their fronts; it can just take a few weeks until the patient feels confident to do this. Once the patients’ have recovered from surgery the breast will quickly feel “normal” to them and sensation should return to normal. Wherever a patient has an incision there can always be a degree of numbness; as the incision is hidden under the crease of the breast this is not normally an issue.