I started as a GS-7 at $40K in a job that had a guaranteed 7-9-11 promotion.

(My previous job I was making $80K)

It sucked but I had to work 2 jobs to make up the difference for 2 years.

Eventually after 4 years I was making the money i left and from there it was off to the races.

I guess what I am saying is you are going to start with another job and a roommate but eventually it will work out. Feds provide great opportunities for promotion.