Can someone link me straight BDSM where the dom uses catheter on the sub ?

if by straight you mean not yaoi then i can't help you xD
but here are some truly awesome lists, maybe you can find smth nice there :p
http://www.mangago.zone/home/mangalist/100188/
http://www.mangago.zone/home/mangalist/43075/

it was for experiment purpose but wow how ironic I already follow them , thanks !

Thanks I'll check them!