Well, I think you will be ok.
Your P60 shows you earned in the last year in excess of the income requirement - and overtime IS included. It doesn't matter that your base pay is less than this, because you did earn more.
Your children in a previous relationship doesn't affect your application either - only if you were sponsoring HER children. You aren't, so you can forget worrying about that.
Frankly, you seem to be in the clear
