Not sure if I can help, but I can share my experiences. Personally I do not get on with overlays full stop, I am and always will be a picker and I have a good old pick and fiddle with the gel. This is worse with overlays because the natural nail is more flexible than a tip and I can quite happily pick and chip at the gel to my heart's content ( i know, I'm such a bad girl). Not saying that this is what your client is doing, but is she is a biter or picker then she may be helping it along its way!!
If the rest of the product is not lifting or chipping then I would say your prep is fine. I find that with overlays when they knock their hands and nails in everyday life movements the natural nail doesn't support the gel as well as a tip and so some clients who are a little more heavy handed just don't get on with overlays. Sometimes I will start them with tip and overlay and then as the tip grows out they switch to the overlays and for some reason everything seems okay. Don't know if it's me or them, but it just seems to work!!
I use the LCN range of gels which are great because they have a wide range for every occasion. For someone in this situation I would use either Fibrique which has small fibreglass fibres in it which just gives a bit more strength and support. Or bondique which is a very flexible gel which tends to "give" more with the natural nail, rather than lifting and chipping against the natural movement.
I note you use a white gel. Is this like a builder gel ( ie has strength) or just a paint on gel ( ie just to give the white colour and has no strength)? If the latter than that may be your prob as it has no strength and therefore is not supporting the natural nail at all.
Okay enough of my usual waffly stuff. I hope that I may have been of help, but like I say some people(like me) just don't get on with overlays, and your lady may be one of them.
