Shower Drain Pipe too Short for Drain Assembly

I think I really messed up. It all started several years ago when I just wanted to replace my shower strainer, because it was ugly and rusty. I threw the strainer away and have spend these past years unsuccessfully trying to find a strainer that fits. My great idea was then to buy a strainer with the piece that it snaps onto and replace both parts. Had to saw and break out the piece of the old drain. Can't get the part that I purchased to fit. Then I ordered a Wingtite drain. I understood the directions to say to remove everything to expose just the drain pipe. After many hours breaking off all of the glued parts, I now find that the drain pipe is a tad bit too short to fit the drain assembly over. How can I extend the pipe now?

Cut it further back and put a coupling and a new section of pipe in.

drain

You would probably have been money ahead if you had called a plumber way back when before you started chopping things apart. Now your only solution is to cut the pipe lower and install an extension up to the necessary level. Not a big job if you can get under the shower, tremendouslsy big, i.e., maybe not a DIY task, if you are on a concrete floor.