TB's have a much more diffcult time maintaining balance when being ridden. An OTTB, especially one that has raced for 7 years, is going to be extremely off balanced, especially when asking for collection. Do you have a trainer or are you taking this task on your own? For the horse to only be off the track for a year, to have been ridden consistantly only 7 months, I'd suggest slowing your progress down a bit. You have indicated signs of a horse that is off balance and bracing against your leg and arm cues. Also, this horse has been exercised consistantly to the left for years on end, he probably does not have the physique to consider higher level work to the right hand side, a side many OTTB struggle with. My advise is to go back to the training scale, which if you are considering collection, I'm sure you are familiar with. I would also suggest getting a trainer. This will have enedless benefits. Work on tempo, rhythm, and balance. Speeding up is also a indication of uneven tempo and rhythm, which is mandatory for collection.