Here are clues that tell you that your code may be too complex:
You have to add "hacks" to make things keep working.
Other developers keep asking you how some part of the code works.
Reading a line of code takes longer than an instant for an experienced developer.
You feel scared to modify this part of the code.
Management seriously considers hiring more than one developer to work on a single class or file.
It's hard to figure out how to add a feature.
Developers often argue about how things should be implemented in this part of the code.
People make utterly nonsensical changes to this part of the code very often, which you catch only during code review, or only after the change has been checked in.
-Max