3 months old infant can't sleep well.

Hi mummies, my 3 months old baby can't sleep well. She is a latch on baby. So she nap while latching or when I carry her only. But when put her to cot she is wide awake. She woke up at 730am this morning. But until 12pm haven't fall asleep. I'm lost. I don't know what should I do now. Even ytd she also didn't sleep/rest well. Is heart broken to see her like this. She poop and drink as usual.