I don't have any advice, but I thought I'd share a little story that will
hopefully make you feel better.
About 2 years ago I wanted victoria beckham's new bob..My hair started out very long maybe 3-4 inches past my shoulders blades and blonde (it was very healthy too!) I brought in ohhh I don't know maybe 4 pictures of the cut from all angles. I asked her very sternly "Are you sure you're going to be able to do the cut?" she was VERY confident, well the front ended up being about an inch ABOVE my chin and the back was butchered...it looked like a man's haircut ...she cut the layers all the way up to the crown..I basically had a 50 year old man's haircut but with a few longer pieces in the front on top of that the color was HORRIBLE it was like blotchy/ashy brown when I specifically wanted a "deep mocha" brown...I mean I would have done a much better job with no experience..I was kind of in shock the first day, but the next day I was devasted...I think I cried for a week and I do not cry easily, to tolerate the cut I took the front pieces and kind of combed them behind my ears so that it just looked like a normal pixie cut, oh and I re-dyed it myself and the color was awesome..
It finally grew out to about an inch past my shoulders maybe like 8 months to a year later..well I went to a different girl to get it back blonde and she turned my hair YELLOW... like canary yellow(and my har is already naturally blonde mind you...)...I told this girl exactly what I wanted as well and again I was not listened too...SO I basically took all my anger out on this girl and told her she needed a new job because she sucked at doing hair and I was going to make sure that EVERYONE knew about it.
So my hair is finally long...about right past my shoulder blades and a normal colored blonde (thanks to me!). Basically I feel your pain...I was traumatized and seriously now have a complex about going to the salon. I just don't understand how someone can go to school, work for a few years, have a picture be brought in for them and STILL suck...
and get HIRED somewhere on top of that! Your hair will take time to grow out, but trust me it will grow back! My hair probably took a year to grow to this length, but yours may take less as it's probably not nearly as short as mine was....feel better!
oh and p.s. both of the girls I mentioned had only been working for 3 years and were very young as well so maybe that'll be a red flag for next time! lol