Betta Fish: Am I cooked?

I've been really reluctant to post here but I could really use some advice. Sushi is 2 years old and while technically my 8 year old's pet, my baby.

-5 gallon tank
-heat around 78°f
-Amazon sword is about 6 months old
planted after anaubis died off?
-amano shrimp introduced 2 months ago teenager brought home a zip lock with like 40 from a biology teacher, a dozen remain that have dodged sushi so far
-moss balls added a month ago
-now have ramshorn snails?
-possibly "seed shrimp" too?

I'm worried I ruined the tank trying to "improve conditions. My initial planting died off and I had a horrible algae problem. I replanted and added drift wood. However, I think the drift wood was too rough and tore fins. And, while I've read the tannins are healthy, sushi laid on the bottom of the tank and barely ate until it was removed. I got a nitrite snail that got pestered to death, (betta wouldn't leave him alone, crawled out the small gap for heater cord and died on counter). Teen then called and asked if he could bring home a couple shrimp, warned him they might be eaten. Lo and behold he brought home over 40 amano shrimp, fish culled them down to a dozen. The shrimp cleared the algae problem quickly, I decided to add some moss (ordered online). Now have something microscopic all over tank, also snails. The Amazon sword has also gotten huge.

Is the tank ok? Should I be culling things? Feeding less? Cutting back the plant? Am I doomed to have a tank over run with snails and mystery mites?

I don't know a ton about aquarium keeping but I'm trying my hardest. Sushi has so much personality. I'm limited by what I can do for the tank because everything basically has to be ordered offline. The closest petsmart is 90 miles away and a real fish store is like 150 miles.