Exercise and hunger
First of all, I think it's really very normal to have slow periods in weight loss. You didn't say how many calories you consume a day, but it's not uncommon to need more calories or be hungrier when you work out with high intensity. I'm in maintenance and eat about 1800 or so a day.
I didn't notice when your surgery was, but every weight loss chart shows fast loss quickly at first and slower after about 6 months.
The BEST reason to exercise is health benefits. If you try to focus on your fitness level and all the health benefits you get from exercise rather than the rate you lose, you're more likely to keep exercising as a long term life habit and the weight eventually comes off. You're also MUCH more likely to keep it off if you continue with a good exercise program.
I'm 4.5 years out and have been the same size and wearing many of the same clothes for over 3.5, so I would definitely say that regular exercise has been the key.
Linn