The way to stop overusing 'I' and 'I'm' is to examine the words following those terms.
Usually, they are filter words -- thought, felt, heard, et cetera -- and are putting a kind of layer between your 1st person narrator and the reader. By writing more intimately, the filter words disappear
For example, 'I felt angry because they were out of cookies' becomes 'No Cookies! Don't tell me there are no more cookies.' or 'Is it too much to ask for there to be enough cookies for everyone.' or 'Never enough cookies. #Deleted bakers!'
And, 'I thought I'm getting fat' becomes 'These pants are too tight?'
Okay, fine, they are lousy examples. You're not paying for my A-game! I thought to myself as I typed out my answer to another question on that online forum.
Not that you should be getting rid of all I and I'm. They are useful for focusing the moment on the character, especially when the character experience is mixed in with narrative passages. As in 'I'm short. Not that it's all bad. Many famous people were short -- Alexander the Great 3'6" Jack the Giant Killer 2'10". The world can crap on short people, thinking them small and insignificant. Just let them go on like that. Never thinking, I'm hiding under their bed with a knife.'
Starts intimate. Drifts slowly away, feels kind of like a character thinking, but is a great way to introduce world building and exposition, then pull it back into intimate with 'I'm under their bed.'