my paed said it is quite normal for little ones to wake at 5am for the first few years.
DD has rarely slept past 5am and is bed at 7pm. with no day sleep.

DS (16 months) is up around 5am as well with a day sleep. Plus will wake a no. of time int he night as he is teething.

You arent doing anything wrong. it is perfectly normal. I was exactly the same as you ( my 2 are 15 months apart in age). And you dont get more sleep, even after #2 is born i am still waiting for a full night sleep and a sleep in past 5am (16 months post #2!!).

Make sure you are eating well and have rests when you can in the day.
x