What was the purpose of the potting soil--was it to bury the seed? Why the aeration? Was it heavy soil--or was it compacted by foot traffic? Won't the starter fert stimulate the Bermuda already present? So it covers over the seed? (I guess, it that case, it wouldn't matter.)I don't do Bermuda--so--lots of questions.
Clearly the best and most needed thing for this lawn is water--and lots of it.
Are you convinced that the seeded Bermuda Sahara is the same color and quality as your original Bermuda sod? If it takes--if it looks the same as the old grass--how will you tell if it "took"?
Are you cutting with rotary or low with a reel?