Okay. Well your strain would have some guidelines as to how long it usually takes. Anywhere from 50-55 days of flowering.
Most autos will be done from week 7-8 when stigma starts, (white pistils)
Bit hard to say from your pics but you say she's into week 3 of flower. It looks around the 20-25 day mark. So if I had to take a guess 3-4 more weeks with nutrients, get bloom +calmag and a micro all from biobizz. I'm running with all there PH + - and there calmag, it's pretty good. The bloom, micro + calmag will set you back roughly 30-40$ depending the sizes you get. But you should be able to get 500ml bottles for under or around that price and you'll have everything you need to finish this grow.
For your next grow you should look at adding some sort of bacteria to your grow. Enzymes and root stims work a treat in soil and good bac will be helpful.
Good luck.