Hey Claire- my dd1 has a reasonably flat head due to being in a hip harness for 6.5 months and being on her back most of the time. It was really flat, but as soon as she learnt to sit...crawl, walk etc, it rounded out (not completely but better than it was). Loads of tummy time is good, sitting her in a bean bag, propped on pillows or rolling a towel up and putting it along side her to keep her head to one side and then alternate.

Shes still pretty young your dd so you have plenty of time for it to change shape. If youre concerned get your gp to have a look and maybe get a referral to a paediatirican.

Hope that helps

Melissa