Here on BW we do not support or recommend the CIO method, as Tracey believed that it destroyed the bond of trust between a child and their parents. She also believed there are other kinder methods to teach sleep to a child, that were just as effective.
Are you familiar with her books and methods for sleep?
TBH I think your lo is SUPER OT, as 10-11hrs sleep a day is too little, and going to bed shattered is causing the EW.
9 hrs night sleep is always OT at bedtime.
Can you post what your day looks like with times so we can make some suggestions.
But basically, I think you need to shorten the am nap, so he is tired enough for a pm nap, and bedtime needs to be a lot earlier until this settles down. We would usually say 6- 6.30pm if a lo is waking at 5am. Sure, your lo will likely still wake at 5am for a while, but it is very unlikely he will wake earlier. This way he will have had an extra 1.5hrs sleep and that will help a lot with reversing the OT.
I also doubt the 5am wake is hunger TBH. A 14 mth old should be able to wait until morning for their milk. My DS is 13 months, a TERRIBLE eater due to food aversion and reflux, but he can wait until 6.30am for his milk now. nly started at 11.5 mths but we did get there.
There is no quick fix to making him go back to sleep - the key lies in reversing the OT and getting him to have a pm nap.
Happy to help more after I see your routine, and what you think of what I have said above.