wow, that is a lot of responsibility at your age. Have you been able to talk to your husband about this, because unless i'm missing something he's part responsible for your pressures? how is he about it all? You need to have some self worth you are a MOM ! that is the most important job in the world & you should know that Mom's with young children are the most important of people, unfortunately it is some times the most taken for granted position in the world & highly underpaid, but you do it because of the love.
I assume that being a busy Mom that you probably aren't getting the balance of nutrition in your system & this is important for both your children & you, & has life long remifications for both if left unbalanced.I also believe you would feel better if some important nutrients were increased in your diet.
let me know if you are interested & i will try to help you & Your sister if you would like!
God bless.