On the note of when the girl in the astronaught comes in with the two silents and Amy is captured, then as the doctor / river and so on didn't know Amy was captured at the same time as girl escaped the space suit, maybe instead of the girl being really strong, the reason she was with the silents then is she made a deal with them that if she helped them capture Amy, they would help her get out the space suit.
- Now this would rely on
-- The girl maybe being able to remember the silents. (Either they allow the girl to remember her or the girl has some sort of talent for remembering them or the space suit 'helped' her remember them (by the fact the doctor created a hologram of a silent from Amys phone / Canton videoed one, it seems that they computers can 'remember' them, we just forget we saw them when we look away, so the suit could always put an image of one in the corner of the girls eye, so while in the suit she would always remember all encounters with the silents)
-- The space suit wasn't created by the silents. So far, it hasn't been explained why they needed the space suit, and when they had Amy why did they not seem to care the girl had escaped the space suit? Either that, or it was created by them, but they didn't need the girl anymore once they had got Amy, and they made the suit in the first place to trap the girl, so they could get the girl to agree to help them trap Amy.