Okay, I am going to put in my 2 cents and ask a few questions. If anything sounds offending, i'm not trying to be..
1. How did you fishless cycle the tank? You need to add an ammonia source such as pure ammonia from Ace Hardware, Fish Food, or a Frozen Shrimp in a nylon.
2. Bump the heat up. Like 82*. If you need another heater, get another heater. The heat will help with growing the BB
3. Do 50% water changes at least
once a day, if not twice. This is going to be too easy in a 5.5.... Wait till you have to do a 75% pwc
in a 25G, in the basement, with no sink. Using a 5 gal
bucket. That's why I am waiting till there's a sink down there to get a 55..
If you truly have 6ppm of ammonia in there, those poor poor guppies won't last very long in that water.
4. I would wait on the blood worms until your tank is cycled... They are very messy, and if the fish don't eat them all, they just add more ammonia to the tank. Actually, you should underfeed by a little and fast one day per week. This will help with the ammonia.
5. For plants, you picked slow growing ones. They will help take a little ammonia and nitrates (They don't eat nitrites) but not much.. If you can get some, get some anarcharis. Not they prettiest plant, but they will eat a ton of ammonia and nitrates, and it grows pretty fast also.
6. Do not, I repeat, do not
add any otos... You are 110%+ stocked as is, your tank isn't cycled, there will not be proper algae for them to eat. They need a very mature (and larger) tank, so they can get enough algae and bio film to eat. They never eat prepared foods. 99% (if not 100%) are all wild caught. They are not schooling or shoaling fish, but they are shy fish and do like others of their kind.. Unfortunantly, you will not be able to put any other fish in this tank.
A couple months after it is 100% cycled, you could add a couple Ramshorn snails, or a couple amano shrimp, or a few cherry shrimp, but keep in mind the guppies will eat most if not all shrimplets the RCS decide to have.
I hope this information and suggestions help. If you have any questions feel free to ask