Hey! As Flint said, stocking is your major issue here. You have fish that will outgrow your tank, improper shoal numbers, and disasters waiting to happen. You're going to need a bigger tank or to find other homes for those fish. I'm going to list out the species you have and their individual issues.
2 dwarf gourami
- dwarf gourami can be housed together, but a 20 gal is too small. One of these fish can stay; the other needs to find a new home away from the angelfish and betta as these fish are incompatible.
2 guppies and their 7 week old babies
- these guys are actually perfect for a 20 gal. Keep em! But you might want to put the females in another tank because guppies can and will overpopulate a tank
1 neon (tetra I'm assuming)
- while this fish is a good candidate for a 20 gal, they are a shoaling fish and need to be with more than 6 of the same species. They often become very stressed when kept in insufficient numbers. Get more and they'll do great with the guppies.
- I'm going to assume this is the common pleco that pet stores normally sell without telling you a darn thing about them. This fish is going to outgrow your 20 gal and even a 55 gal. They get huge and they poop. A ton.
2 clown loaches
- another extremely poor choice. These fish are shoalers who need large groups and they grow over 12 inches long. When housed properly they need a tank larger than 100 gallons.
- had to look this one up. Most people will know it as a Synodontis angelicus
. Again it's going to get too large for a 20 gal.
- Another one to look up. Synodontis nigrita
. Another one that will outgrow your tank.
red tail shark
- these guys are known troublemakers. As they age, they tend to become belligerent to other bottom-dwelling fish.
- I have no clue why stores still sell this fish. They get larger than 12 inches and are a shoaling fish. You'll need an aquarium larger than 100 gallons to safely house them.
1 female betta
- could live in the 20 gal if it weren't for the gourami.
1 angel fish
- A shoaling cichlid that does best in groups of 5. They also get really tall and need tanks larger than 40 gallons.
Honestly, to avoid overwhelming yourself, I'd rehome everything except the guppies, neon tetra (only if you are willing to get more), one gourami, and betta (if you are willing to get her a 5 gal tank by herself). It's not your fault, but you have a lot of incompatible fish. Not even upgrading to a 55 gal will solve your problems as the bala shark, pleco, and clown loaches will outgrow that.
This website has my favorite profiles for fish. They include things like recommended minimum tank size and average adult length for fish. I highly recommend looking up the fish you've acquired in their profiles.