I think I just got my Amazon store audited because I ignored resale certificates for 6 months

Okay I need to get this off my chest before I completely lose it. I started my Amazon store 6 months ago selling home goods I source wholesale. Someone in a Facebook group mentioned I need a resale certificate and sales tax registration but every state has different rules so I just… didnt do it. Figured Id deal with it later when I had more sales. Big mistake. Huge.

My supplier kept asking for my resale certificate to skip sales tax on inventory and I kept sending them my EIN thinking that was enough. They finally stopped shipping to me last week saying they need the actual state form or theyll charge me tax retroactively. Fine whatever but then Amazon emails me yesterday saying theyre reviewing my account for tax compliance issues because multiple states are flagging my sales for uncollected tax. Turns out because I have FBA inventory in 5 states now I have nexus everywhere and Ive been collecting the wrong rates this whole time.
I went to check and realized California wants their own resale form CRT-61 renewed every 3 years Texas has a different one and some accept multistate but not all. I thought one EIN covered everything. Now Im staring at potential back taxes penalties and my account might get suspended before I even hit 100 sales total. Spent 2k on inventory thats sitting in warehouses while I scramble to register in multiple states.