Help/any advice please?

hi
right im 5ft 5ins and 169lbs down from 248lbs just over 13months ago, which I have done by walking more and counting calories and keeping to my 2000ish a day.
thing is I have been playing around with the same 7lbs since Christmas and am losing. I am thinking maybe cutting right down to be bmr of 1230 for a while?
the thing is I have a half marathon in 5 weeks and other events during the year.
I think I maybe consuming to much sugar does this result in weight gain, but as im running im conteraction somehow???
my overall aim is 126lbs so still got someway to go
thanks