I'm training for a sprint triathlon this summer and it's TOUGH when you have kids around. Mine aren't so little (7 and 10) but the 7 year old is profoundly autistic, and as a result DH and I have set up our schedules so that we work opposite shifts. It's great for childcare, but not so good for getting time to yourself. My husband's schedule is four nights per week, Wednesday through Saturday, so I have to work around that (which means no weekend day training for me since I have to take care of the kids while he sleeps).

My current "training" (and I hesitate to even call it that) is four workouts per week during my lunch hour--I work on a college campus and have access to the gym and pool, so I can run over there and put in 45 minutes on the track or treadmill or in the pool. On Saturday mornings my son has a swim lesson at a nearby gym, so my DD plays in the family pool during that lesson and I go to the lap pool and swim for 20 - 25 minutes. Not great, but you take what you can get. In theory I also do pilates at home after getting the kids to bed, but, um, I haven't done that since January! Biking is the biggest difficulty. Currently I bike to work (13 miles each way) one day per week, on one of the days when DH is off so he can get the kids off to school. I'm hoping that when summer comes I can increase that to two days per week and one weekend evening after DH wakes up for his "day" but before he goes to work. Right now it's still too dark in the evenings for that.

My sister was in a closer position to you with three children and trying to get in workouts when she could. She and her husband would trade workout times--she'd ride her bike to the gym, swim/run there, and then ride home then her husband would turn around and do the same thing. Once her infant was six months old or so, she started signing her kids up for the childcare slots at the gym, which made it easier to schedule workouts without relying on her husband being home, although her entire week seemed to revolve around when she could get the childcare slots!

As for eating while breastfeeding, just listen to your body--eat when you're hungry and really focus on eating well, not just scarfing down calories. Don't worry about your own weight--your baby's weight will let you know if he's getting enough through breastfeeding, but if YOU feel unusually tired or run down (I know, hard to tell what's "unusual" when your schedule is all whacky), you might need to be eating more. Drink lots of water, of course. I had some supply issues with my first baby and ended up taking fenugreek to help increase milk production, but that didn't happen until she was older.

Good luck!

Sarah