I cleared all of act 1 on nightmare and wanted to jump into act 2 with some random people but I hit a wall. When attempting to join a public game I only have the option of joining A1 Part 1-8 even thought I am on A2 P3. I am even unable to go back and play public normal games due to this. Is there any way to fix this?
Most likely your level is too low. Public games have strict level ranges that you have to be within. You could always start the quest yourself and then make the game public.