Mine took about 5 days to come in after I had a PPH of around 1100 with my first and a little bit less with ly second. A LC that saw me for a home visit with my first said that a bleed can delay your milk coming in as your body needs to replace it's volume first then make milk. I found the first week for both exhausting as both of mine did the same thing as your little one is doing. Give it time, it will come.