Nice tank!
About the amount and frequency of feedings. From what you said and since you have nitrites I think it is safe to assume your tank is cycling, this is what I would do (again this is JMO - like theysaid in that newbie pitfall thread take everyone's advice with a grain a salt and always get more opinions)
Feeding:
-More food = more waste
-While you're cycling, your tank can't handle much waste so less feeding is better.
-I would feed every other day or even one day yes, two days no while cycling. You can balance this with the frequency at which you do your PWCs. If you need to do 2 PWCs per day to keep your ammonia/nitrites below 0.25ppm then you are feeding too much and should feed less.
- As a general rule and without going to extremes of course, it is better to keep your fish slightly underfed than to overfeed. What I mean is that it is better to err on the side of caution.
-As your tank cycles you can increase the frequency of feedings. Personally, I like to feed "well" (I'll explain) one day and lightly the next day and so on.
-What I mean by feeding well: you may come across the rule that you should feed what your fish can consume in 5 minutes (or 3 minutes depending on where your read it). I found this hard to judge when I was starting, so I look at how vigorously the fish are eating. I feed little amounts at a time until the fish start to eat slower and their bellies barely start to round.
- The bloodworms once a week are a good idea, feeding your fish a varied diet to suit their needs is always a good thing. Platys are omnivores so the bloodworms are their meat.
While cycling:
- Do as many PWCs as needed to keep you ammonia and nitrites below 0.25ppm and towards the end your nitrates below 40ppm (some conservative people, like myself, will say below 20ppm - there is no such thing as too many PWCs)
Sorry for the novel but I hope it helps =)