4 months old! Time needs to slow down!

My daughter is already 4 months old! Time is flying by. She is already starting to laugh and is growing so fast. I feel like I was just walking into the hospital to have her! I never thought I would have a daughter after having my son. She has made my life so much better! Anyone miss there babies being new borns? My son is 2 April 14th! I already am having baby fever just by looking at his baby pics and hers. Anyone get pregnant while exclusively breastfeeding there 3-4 month old? I am not trying for a year or more just curious. :)