i use the same glue and i get a 4 to 6 week hold. So i believe you need to apply more layers, instead of one tiny. I use a minimum of 2 layers, but mainly 3 and i paint it on the whole area for the best attachment, that means on my whole head.

So maybe you just need to use more glue and maybe not just on the edges. And let him dry for 5 min at each layer, befor you attach the piece.

If this doesnt help, then the glue doesnt work with your bodychemistry, so you have to try a other adhesive.

And btw. wait a day between a fresh attachment and a shower.