I agree with the others that mentioned Chiropractic. My kids have been checked at hours old after coming out of the womb. The trauma new babies can go through can range from mild to more severe when coming out. Specially if they were big babies and cramped as well.
We corrected my sons head position by the 3rd month. He would only turn his head to one side.
Not a big deal in infants....and the good thing is if you get it corrected now...it doesn't set them up for lifelong problems later.
Newborn and infants have platelets surrounding the brain. Soft for a reason obviously. To get a perfect 'round' head...our Chiropractor had us 'kissing' each side of our children's head just above the ear area. If you feel that one side or the backside is not even or flat...as you stated...then by making the puckered 'kiss' face...you can LIGHTLY suck on the head that helps move the platelets around.
Now hopefully no one gets the idea that if this light sucking is good the suction from a vacuum is better!!! NO!! hahhaa....it doesn't work that way.
By doing a little each day....even 'coneheads' you can LIGHTLY press each day and shape the head. Just by moving your hands around and lightly pressing ...over time you can get it nicely round and back into shape after birth.
Pretend it's someones badly black and blue bruise...and it would be painful to press on it too hard....be THAT gentle. Don't try and do it in one day. {;o)
And so clearly then for the flat part you do the LIGHT suction 'kissing' to help to move things out.
Babies are amazing. And how God made them to be able to BE this pliable and form able to be able to come out of that small canal when born ....yet just as easily 'damaged' by the same process if you don't put everything back where it belongs.
Get references from friends or family. Find a Chiropractor that works with children would be great. But that is the best and most safest way to accomplish what you want. And you're doing your baby girl a big favor for her future as well.
And yes, both my kids have perfect round heads! HA....not to mention all the 'other' added benefits of the Chiro care....they've NEVER had any ear, nose or throat problems. Fever only associated with teething.
Many many pluses.
I wanted to avoid a story - cuz I have 26 yrs of them.
..... But I had a couple of friends who's babies hated tummy time because they couldn't lift their heads or turn. They were subluxated(meaning pinched, irritated, keeping them from being able to move freely) in the first two vertebrates. For your daughter she may be hating it for the same reason. SOMETHING could be irritating her. Or she's just not ready. Many people believe that because babies are so pliable, cartlidge ...that they can't be 'jarred' or have areas that get impeded, pinched nerve, etc. Not true. They just don't have the pain involved as an adult would have BECAUSE they aren't solidified yet. That's why if you catch them before they are 18, or keep their spines in good health, they can enjoy adulthood with alot less problems.
Sadly alot of people still look at Chiropractic like it's some weird form of care. We'll spend our lives going to dentists, eye docs, pediatrics, OB's....every doctor for every 'part', but not Chiropractic to take care of your whole FRAME. Your spine is your framework. If in good health it helps the body to bring nutrients to all the bodies organs and healthy brain function. But sadly in our society we'll spend more time at the hair dressers or getting nails done every week....then thinking about, realizing, or worrying about the whole framework.
A friend of my Moms son, at 15 had scoliosis so bad, that he was constantly harassed and humiliated at school for being the next 'hunchback'(kids are so cruel). He stopped going, and continued to refuse to go to school citing that he was going to drop out. I urged my Moms friend to take her son to my Chiro a give him a try. By the time he was 18 he stood as straight as an arrow!! Got rid of several other health issues....and went on to becoming a professional chef in some famous hotel somewhere.
Either way it's worth checking into.
Good luck.