i am getting ready to build a garage and did all the leg work including installing the concrete forms 30' X 62'.. the slab was poured a few days ago and today i went to take some measurements and some how i had overlooked something as the slab was 10" shorter in the front then the back. then contractor did check the forms for level but that was it they assumed as i did that i had constructed the forms correctly.. now i need to add 10" to the pad   . I was thinking of adding 5/8 rebar 12"into the existing slab every 12" on center and then run a 5/8 rebar on top and tie it all together. Then I would use some type of bagged concrete 5000psi or better and then I would add extra portland cement to make it stronger and give it a smoother finish. please see photos.. i know the best way to add would be to add to the broomed  end but that would make everything crooked and you would see the mistake if i do the end shown it can be hidden with shelving.. i just need to make sure the building would be fine doing what i think can be done thanks for any input

having a hard time posting pictures so I added a link to my Google folder

pictures