1. sativas come in all shapes and sizes, a very very sativa like love potion #1 or acapulco gold will take a long time and be very tall. The potency is based on nature and nurture. If your plant has great genetics and you grow it with enough light/correct amount of nutrients, you may do very well.
My sativas are over 3 feet tall and before I wen 12/12 the tallest might have been a foot tall. You might be better off using the females as mothers and taking lots of clones and flowering them under a better light with little to no veg.
sativas are a historically stretchy strain. using a t-5 is quite simply, a mistake. i'd (as mentioned) take cuts and grow over. a t-5 will not penetrate too far into the canopy. i suggest a scrog. if you proceed from here with a t-5, your plants will stretch into the ceiling...