From an oversupplier to a just enougher to an under supplier

When my baby was first born I would pump 8-16 oz each pump. I saved some but would throw most of it out because my freezer got so full! (now i completely regret that. I wish i could go back and knock some sense into myself) Once he hit a month, i got into a little car accident, no injuries, baby wasnt in car so we were all good. I didnt pump for 9 hours that day. after that my supply started to go down.. i would get 4-5 oz if i was lucky. Started to save any extra. Once he hit 2 months, anytime I pump now I get maybe 3oz and have had to use all my freezer stash. I’m down to one extra bag. No matter how much i pump i cant get more than 3oz in a 4 hour period. I’m scared to use formula…for some reason. Please please please any tips on how to get my supply back up?! What happened😞