Serious breeders set up species only tanks. I doubt you will ever breed egg layers in such a mixed community tank.
Larger groups are often better.
I would add more plants, stop trying to mess with your pH and enjoy your fish.
If you want to breed something, start with an egg layer that's not as difficult as the Tetras.
Since you have 2 sick fish, something is off with your tank. You need your own test kit. API Master Test Kit is the usual one.
Anytime I have something off in my tanks, my first act is a large water change. Usually 50%.
If you do decide to try breeding again. You should also research about types of food. Most serious breeders feed tetras live foods to condition them.
I've seen breeding behavior from my fish just after water changes with slightly cooler water and also with the almond leaves and also when my tanks have lots of plants and the water is very very clean and they've been getting a variety of frozen and live food.
Just understand you aren't going to make money breeding fish. Most stores will only give you credit for the fish and it will usually be a fraction of the retail price. So if you want to breed fish, breed a species that you really want to breed, that is possible to breed and don't think about making money on this because typically you won't.
Community tanks are not typically successful breeding set ups. Dividers can stress the fish.
Consider setting up a 5-10g tank and breeding Cherry Shrimp. Much easier and they don't eat their eggs or babies. No fish in their tank, except Otos if it's 10g or larger.
But you have to stay on top of maintenance. You have to do your water changes every single week.
I would never want to discourage someone from breeding fish. I think it's a great thing to do. But I think you need to slow down and step back and do more research so you're not wasting time and money.
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