If this were my dream I would interprete it as...
A knee is of essential support. So to have a busted knee indicates the feeling of loss of support, feelings of inadequacy. The knee injury seems related in timing to the appearance of the guy you have a crush on. So, basicaly he makes you feel imbalanced and very unsure of yourself. A hospital could mean 2 things, and in this case I'm inclined to say it indicates a sense of helplesness, a sense of losing control over yourself, because the first thing you do when going there is make all the people in your dream already present with you to come with you to the hospital. Getting everybody to come along shows a high need of seeking support and help. You wouldn't be seeking it if you did not feel you lacked it.
But eventually a hospital is a place of healing... and it heals you by giving you a metal kneecap. Metal is exactly the cure you were looking for: it stands for strength of character. So, it's no surprise that you can display a cocky attitude once you have the metal kneecap.
The mentioning of a future flight indicates that once you regained your strength of character with the metal kneecap, you are almost ready for a new stage in life. Although you seem to think that perhaps your newly gained character might cause some negative reaction from others, may make them feel insecure about trusting you.
So, in short, the dream mirrored your own feelings of helplesness and insecurity around your crush, that you somehow regained strength again through some unknown means, but that with that strength it's time for another stage than having a crush (maybe you develop something more fruitful than a crush, or maybe you're finally ready to notice someone else... who knows?), but since this is all so new you're wondering whether it might not surprise people who knew you differently before, enough to make you fear they wouldn't trust you. But it seems you're pretty happy with the new strength and sounds like you're feeling "take it or leave it" if you don't like it.
Hope that helps
