hi

i was wondering...how did you come up with so many fish??

In my case....I had in begining two goldfish and a comet and my son got a red platy on a b-day party, that turned out to be very pregnant...and end up with 10 red platies and the goldfish....that is when I got interested in getting a bigger new tank. Now fish is my hobby...
Going back to your tank...I believe that your filter will tell you how many fish you can have in the tank...it is good that you make water changes every week for all those fish...but still its is too many!
How many fish do you have right now...you were saying that some have died...I'm sorry about that...

Depending on how many fish is left you may want to split half the fish to another tank...unless there's not toomany
you can tell also when they are swimming and "socializing" if there's not enough room for everyone.

I wolud like to know how are you doing right now...hope this helped
Good luck!