Hi fishrule
I with agree with angelfish about the betta.
I came up with 32" (I could be wrong) for your existing stock excluding the crab and shrimp):
7 platys 14" (2")
2 swordtail 10" (5")
1 Paradise Gourami 2.5" (2.5")
1 betta 2.5" (2.5")
2 tetra 3" (1.5" or larger)
Red clawed Crab....not sure..I read up to 4" but that includes their legs.
I wouldn't add anything else, as you are overstocked.
How old is your tank? Is it cycled?