If it's any consolation my youngest (who is 11) only learned the actual alphabet in the last couple of years :) He did letters and blends til he learned to read (which took him til 8 or 9) and at some point after that he learned the order mostly from his older sister who would sing it with him. I'm still struggling to get him to write in lowercase though he can at least read lowercase now as well, there was a time where like your son he could only read and write uppercase.

Sounds like Adam is going great :)