Hey Joshies mom my ds is now 22 months old and he still does the same. He can't hold on for more than 10 hours with an empty stomach so i just go into his room at the 930 hour mark and in his sleep i pop the bottle (which he drains) so technically he doesnt wake for the milk.If i dont do this, he'll wake at the 945 hours of sleep cranky and hungry and will not go back to sleep.
Im ok with it, my ped told me that refluxer kids (which my ds was and i think still is on some days) have trouble keeping empty stomachs. Also, it is ok when toddlers under the age of 3 can only hold on for 8 hours without a meal.
So as long as it's not a trouble for you, i wouldn't worry too much. Some kids just want their milk!