How do I get over a plateau that I've been stuck at for 3 weeks?

Age: 20

Female

Height: 5'5

Start weight: 159 (June 2008)

Current: 147

Goal: 125

I have been stuck at 147 for 3 weeks now. I've lost 12lbs and I have 22 more to go. How do I get over this 147 mark? 

And, is rock climbing 3 days a week enough exercise? Along with a very active day, 7 days a week?

I eat 1400 (+/- 100) calories a day, usually a Boost for breakfast. Lunch and dinner varies. Lunch is usually whatever the children I watch are eating (which is always healthy) and I make dinner 4 nights out of the week. The other 3 nights I have sushi. Always a tuna avocado roll. Just 1. For dinner I like to incorporate tofu and veggies. Rarely meat, and it almost always contains cheese...is cheese really that bad for me regarding its fat content?

Rock Climbing is always a challenge. I always go home sore, that is why it's only 3 days a week. I usually climb for 2 hours or more. I also take the kids on walks 2-3 times a day. Long walks, and I always push a stroller with either 1 or 2 toddlers in it.

change something.  you haven't told us what/how much you're eating, so i won't comment on that.  if your exercise routine hasn't changed for a long time, your body has adapted and you've become too efficient at your activities of choice.  try something new to challenge your body.

Eat more for a while

I recommend:

Less cheese more veggies and a lower carb fat/protein source -- maybe a boiled egg or two.

Rather than a roll get sashimi (no rice).

I've got some plateau busting ideas..

- have a fibrous carb day of just all veggies and protein (fitness models and body builders do this to get out of a rut).  Also on that day, do split cardio so say, 20 min. in the morning and 20 min. in the evening.

- HITT cardio

- bump your cals way up to say 1900 and then the next day back down.  It revs the metabolism.