How to floss with bonded retainer!?!??!

It's so difficult!!! I've tried using the piksters they recommended, but even they are too big to fit in the gum line, and if I try to force it it really hurts my gums. Is there any other way I can floss, or do i just leave it????? (Also, I read that people use a water flosser, but they are WAY too expensive for me atm)

Thank you in advance!