Bulimics: How long did it take for you to get tooth decay?

I'm not bulimic, but for over a year i've used throwing up to get rid of unwanted calories, but only occasionally like once every month or 2. For the past 6 weeks i've gotten worse and can't stop, i only purge once or twice a week though. I don't always binge i just feel guilty for eating even if i've eaten little enough to lose weight, i guess i feel like i've eaten more cuz i only eat once a day, so maybe it does count as a binge. I'm being really careful and rinsing my mouth with baking soda after purging to neutralise the acid and not brushing my teeth for a while after and trying to drink loads of water before i purge to dilute the acid. Will any of this help? I know it's really bad for me but i can't stop and don't want cavities and i know it messes up your insides too, i don't know how to stop and don't want counselling again or to tell anybody, i'm going to deal with it myself. How long did it take for you to start having problems with your teeth and how often do you or did you purge?