Well, 23 a3 definitely would've gotten hairy for you, but I don't think you should resign quite yet, as you have some interesting possibilities. Of course, unfortunately you are still the exchange down, but you do have two options: 23... Ke6 and 23... c6.
It's true that you will probably be lost in the endgame after 23... c6 24 Rxe5+ Kf6 25 ab Kxe5 26 ba due to the fact that you have to waste a lot of time capturing the knight...but I still think it's a good idea to make your opponent demonstrate the win there.
Also there's 23... Ke6. 24 ab Kxd5 25 ba Ke6 probably still wins for White, but he has to be careful. Then there's 24 Rb5, which looks quite good, and probably is...but after 24... Nc6 White should play 25 Rxb7 Bd6 26 b4... and not the plausible 25 ab b6 when suddenly Black has the monster threat 26... Nd4 looming (26 Nf7 Kxf7 27 Rd5 Ke6 followed by 28... Nxb4 and Black is winning).
I thought I was in a good position and should have won but then played badly. I thought I misplayed the endgame and was lucky to draw. I've been trying to get better so any advice on my playing is appreciated thanks!