I am a hobby grower so I feel your pain. Its always tuff when your girls are not perfect its worse if they are he/she.

The thing is with your bag seed is that I suspect it was a seed from a plant that hermied. Odds are then that any seed you plant could turn on you. It just might be in the genetics of the seed.

I assumed you were using soil. I find for a new grower its a little less complicated. Soil is much more forgiving of temp and PH changes. Ofcourse if you stress a plant out enough it can create a hermi. It has been my experience that it is not easy to stress out a plant enough to make it polinate itself, it seems to depend on how stable the pheno is for each strain.

It is certainly easier to work the kinks out of your grow with bag seed. I did it and I know many who have started with bad seed as well. Once you got your room together really look at purchasing some good clones or seed stock. You will not regret it if you take the time to get the correct strain for your grow space and personal needs.