I'm not clear- you're running ONE 2-bulb T5 fixture over this tank, or TWO fixtures (total of 4 bulbs)?
ONE fixture already puts you at the top of the "low light" range (I know, b/c I've got one over my own 29gal), so if you're running 2 you either need to drop one, or add CO2 to the tank.
In regards to your crypt question... unfortunately, it's impossible to predict for sure. Different plants will grow differently in different people's tanks. Actually, they'll even grow differently in the SAME tank- just move a crypt a few inches over and sometimes it grows entirely different.
Keep in mind that plants are always "reaching" for light- so a crowded plant often will grow a bit taller than a plant that isn't so crowded (as long as the light isn't completely blocked off).
And no, you definitely don't have too many plants for your tank.
You may not need to fertilize depending on your bioload- what do you have this tank stocked with? There's a good sticky on fertilization at the top of the water parameter forum, too.