Your RT3 is high, but your FT3 is high, too, and it's the ratio of FT3 to RT3 that's important, not raw numbers. In my opinion, your numbers do not show RT3 dominance.
Your FT3 is is high, and that needs to come down some more, even though it was even higher in April (please verify those FT3 numbers for April and July). At the same time, your FT4 is below range and has to come up. I think you should talk to your doctor about decreasing the Cytomel and increasing the Synthroid. That will get your FT3 and FT4 back in balance. When your doctor took away part of your Cytomel and replaced it with Synthroid, he didn't prescribe nearly enough Synthroid to compensate for the decrease in Cytomel. Overall, your medication level has dropped significantly.
What are your current symptoms?
TSH (range 0.450-4.500)
Oct'09- 4.340uIU/mL
April '10- 0.07
July'10 0.082
FT4(range 0.82 - 1.77)
Oct;09 1.55 ng/dL
April '10 0.17
July'10 0.60
RT3 (range 90-350)
Oct '09 352 pg/mL
April'10 44
July'10 166
FT3 (range 2.0- 4.4)
Oct'09 2.8 pg/mL
April'10 15.4
July '10 6.7
Ferritin (range 13-150)
Oct '09 32 ng/mL
April'10 18
July'10 36
currently taking: 35 mcg cytomel, 25 mcg synthroid, 10 mg hydrocortisone
I have no personal experience with Cytomel-only therapy, but I do know of people who have been treated with T3-only temporarily. Dosage is very individual, and what others are taking will not apply to you.
Food does not affect Cytomel like it does Synthroid. You don't have to fast before taking it. Once again, when to take your last dose is very individual, and you have to experiment with the time to see when it provides the best energy boost without disturbing your sleep. I'd start out not taking it after 3 pm, but that's just a starting point.