I did also. Was approx 8stone when fell pregnant, 10stone when babies born both times, then struggled to keep it at 8stone as would constantly drop under.
In the end I basically made myself drink a glass of milk and eat x2 biscuits at every feed!
So when ds1 was 4 months I was 7.7stone. By 10 months I weighed 8.5 stone and was 4 months pregnant with ds2.
So my day would be something like:
7am - feed baby, drink milk and have biscuits
8am - eat breakfast ( poached egg, x2 bacon, beans and toast)
Lunch
2pm feed baby, drink milk and eat biscuits
Dinner
9pm feed baby, drink milk and biscuits
I also added cream/ butter etc when possible ie to mash potatoes etc.
Now children are 3 and 4, I still drink milk and have cookies :) every night before bed and still add cream etc to meals when possible. I am 8stone approx ( can go down little but usually stays around there)