Is my tank overstocked?

Maybe just a tad bit overstocked, but just keep up with maintenance. Don't add anything more.

Also I love your plant choices.

I do think it is overstocked, I bet A lot of your fish are not full grown and you may have issues in the future. The torpedo barbs should really be in a 70 gallon or larger. The zebra loaches should be in groups of 4 or more. and the honey gourami shouldn't be in a tank that is as crowded as this. They are shy and do best with other slow moving fish. The torpedoes are not a great tank-mate for them, neither are the other gouramis. They are not really aggressive, but they want to find a decent size territory for themselves. They may not defend the territory from anything other than other honey gourami, but without it they could get stressed and may not compete for food once they are stressed.

I am curious how the fish are doing and how long you have had them all. I know thw water is good, but how about re hominghavior? Hope they are well, but I would consider rehoming some and keep a close watch on the rest.

It is overstocked.

But if you do water changes to maintain the water parameters how they are then you are good. Remember to keep up with essential weekly water changes. Add a anubias plant for more decor and live plants keep the water conditions a little better.

Totally..

Your good up until the yoyo loaches. I would get rid of 2 of those, as well as the pleco. Then you should be alright.

yes it is overstocked but you are helping by your mantaince. but what happens if you go on vacation, or just forget to change the water, dead fish is my guess