Photos will help - but my suspicion is that you have a 'bay window' in front which means that the hip measurement is not all that relevant.

To have the aprons fall straight you might have to add four or even six inches to the hip measurement as there is probably quite a bit of fresh air at hip level which the kilt needs to enclose, but check that the top of the kilt is positioned correctly.

If the front of the kilt is not at the level it was expected to be by the maker, that could cause odd distortions.

You'd need to explain this to your kilt maker in order to get the correct shaping if simple adjustment will not work.

Anne the Pleater