Another First-Timer Looking for Answer

Ok guys, first of all forgive me for my language barrier since english is not my first language. :D

anyway, i have some question about my baby since this is my first time growing any plant ever in my life. which i didn't even planned at the beginning that it would turn out to be serious gardening for me. :)
Last Desember i threw a bunch of seeds from my weed i'd bought on my backyard and after about a couple of weeks i noticed that they are growing n there were 8 of them. so i moved them into pots n grow them indoor. (yet, only one survive until today. :() The following week i figured from the images i found on the internet if those are sativas, which is pretty common for that kind growing in southeast asia.
So, today it's about 6 feet tall from the soil. i use five 23 watts fluorescent bulbs on top and 1 about-2-feet-or-less fluorescent tube on the side attached to the wall. and i put the lights on for 12/12 cycle started about 6 weeks ago or more. luckily i started to see the female pre-flowering (they called those fuzzy little hairs 'pistils', right?) on the 4th weeks.

my questions are:
1. why don't they start blooming after i put it on the flowering stage for such period of time? because the pistils are stay the same size even though there are much more showing up.
2. am i being impatient or sativa takes longer to mature before it starts flowering? it keeps growing taller though.
3. should i add ultraviolet tube to make it bloom faster and better?
4. why the leafs at the bottom part keep turning yellow which later became brown n dry ? not many just a few. is it normal for the plant on the flowering stage?

i will appreciate any input. thanks for your time guys.
again, forgive my english. :D

Bottom line is that some sativa strains take forever to mature! I finally chopped one after 13 weeks of 12/12 and it looked like it could have gone even longer! Just be patient- and try an indica next time! Indicas are much better suited for indoor growing- smaller with a faster harvest.

Granny :hippy:

what?! 13 weeks and still not flowering? just like you said, that's forever!! phew! i think i have to be extra patient then huh? lol so are you growing indica these days? yea, i may try that n get the seed online someday. really wanted to try that white widow kind. it's hybrid right?

so what about the yellowing leafs, is there something wrong with it? and what if i add another ultraviolet light, doest it matter? any idea anyone?

i assume my kind of questions already been discussed before in this forum board, yet i would appreciate so much if there is anyone else that had any experience grew n successuly harvested sativas before and would like to share any tips to me? thanks a lot ya!