Bleached Hair to Black Hair, Need Advice?

I have always had dark hair since i was wee, i've had it coloured a few times by the hairdresser up until about 3 years ago where i have been colouring it myself. I have only had it between Black and XXL's Blue Black, up until last month i decided i wanted to go blonde, so i went and bought bleach. First bleach i got a very golden blonde from, hair still thick and manageable to which i quite liked and left for a couple of weeks quite satisfied. But then a mate suggested i bleach it again and stupidly i thought ill stick it on for a shorter time to lighten it by a couple of shades. Which i was successful of, noticed the day after that hair was breaking off and snapping, when wet especially. I have bought treatments and used Argan oil which i previously had and used anyway on my hair (since i have had weft hair extensions in and out my hair for the past year) The condition of my hair is better, stronger but a lot thinner now. All i can think about is dying my hair back black, which is pretty close to my natural hair colour anyway! Because my hair grows in VERY fast, i already have almost an inch of dark brown root coming in and i am NOT bleaching my hair again! I keep trying to remind myself that i can pop the extensions back in to help it look thick and full again to give my real hair time to heal! As when my extensions are in, i leave them to dry naturally with the Argan oil since i have a great natural wave to my hair anyway. Something needs done as i have a wedding in a few weeks. I just don't want my hair to turn to mush dying it just this one more time!! So i need advice. Don't want to wait til last minute incase there are any colouring disasters, so thats not an option! Basically just need reassured that im doing the best thing for my hair UNDER THESE CIRCUMSTANCES?