First Grow Ever / Indoor 400w metal halide

hey i have here 1 bag seed ( in 3 gallon pot) and 2 white widow seedlings ( under cfl light) and
WELL here my PROBLEM i have been vegging the big plant organically with out any nutes for 1 month and 2week and it grew slow as fuck and i just started puting nutes in it about 4 times so about 1 week and 3days and I wanna know why it grew so slow even tho i had it under 150w cfl lights for 3 weeks and then a 400 watt metal halide why didnt it grow taller before i started puting nutes on the 3 gallon pot ? but what do u guys think for my first grow is it alright or is it really slow and when show i start to expect buds ?

That's really small for that old under a 400 and 250. How far away do you keep the light? What size pots?

well i started the big 3 gallon on a 42w fo a week the uped it to a 150w of cfl sprils daylight 6500k for 2 more weeks then switched it to A 400 WATt MH for 4 weeks now but i only started nuting on the third week after the 400w being on with a NPK of 15-5-5 and it seem for the past week its been blooming really quite fast and i keep the light 18inch from 3gallon pot and about 20 inch from the seedling but the cfl is covering most of the mh light ? and the seedling are in just a starter cup i bought 1 for 3 shouldi just keep doing what im doing or is there a way i can make it taller then it is and it only like 5-6" tall but it def indica so i expected shorter plant but not this short !! and i only have the 3 gallon pot under a 400watt MH bulb and advice ? i keep it on a 18/6 right now planing to switch after the first week of April since it only march 23 ? and the 3 gallon pot one started on fuck feb 5 HELP ME PLEASE )

i wanna switch it to flowering after the first week of April is over ? good or bad i assume its gunna be at least 8 to 10 inches by then ? sincei started nuting witch has a drastic change in growth rate from just organic growing