Hey, i am also a female bass player.
I use this Kilpatrick harness:
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I have found no issue with it as you can adjust the front.
Also gives you great support at the back.
If this is the one you are using and still have problems with it, i suggest you try on as many different bass harnesses as possible.
Find out what other bands are using and ask to come to their practice nights or head to a competition day with many different bands.
There is also a option to have one specially made but this can be costly