Period Panties

Mia
Anyone use period panties? I'm looking into buying SheThinx but I'm not sure if it's the right way to go. If anyone has used and has any advice, please let me know! 
Just some info on me: my periods are irregular and I can't use tampons. I have interstitial cystitis (basically constant UTIs) so that would worsen the bacteria. Anyway, pads are expensive.