Why is my skin flaky dry all over?

my skin has been severly dry since i was 5, i have tried so many lotions, they will help for about 2 weeks and then its lke my skin becomes immune to it. nothing keeps it mosturized or soft. and my parents dont care enough to take me to a derm. so any advice???? its so dry that when i take my cloths off you can see flakes on my cloths of my skin