big gap in front seat after leather install

I am sure I have made a common mistake or something but once I got all the leather on and I reconnected the back rest back onto the lower portion there is a pretty decent gap I would say about 3" or so,when I compared it to the passenger side what I noticed was it was fairly flat,on the driver side the front appears raised and the whole bottom portion not flat.I hope I am explaining this well enough I can't get a picture of the problem yet because its going to get the carpet installed and I need the driver seat in there. any ideas of what has happened?

Im talking about the front seats by the way sorry.

It's possible the seat back was cut a bit short.

Please post a picture.

I will get a picture after work tonight.when the seats was out of the car and sitting side by side you could see the drivers side one was higher in the front,at first I thought it was just the adjustment you can make on the seat,but that moves the whole seat not just the bottom portion. The first picture will show the gap,I won't be able to show what I just explained until the carpet gets installed and I get the car back. Then I can take it apart again and show you all what I mean. I was considering some washers in the back to raise it up but I know that is not the correct fix.