Trying to conceive while breastfeeding. Any advice??

Hi! My husband and I have a 9 month old daughter and we would love to get pregnant again. I first had my period a little over two months ago and was very excited to have a regular 29 day cycle after that, so we decided to try. Now I'm on day 38 and still no period. I've had all negative pregnancy tests, so that can't be it. I'm sure it's out of whack because of breastfeeding and my little one still doesn't sleep through the night. Any advice? It's hard to cut down on the breastfeeding because she has always refused a bottle. I'm open to any and all advice so don't be shy!! Thanks :)