I've just got nitpicky things that "I" would do so... it might not be helpful.
I'm assuming you know about the typos but I'll put 'em in anyway
first line: "sighed"
Second line: 1. I'd drop "even." 2. I'd also drop "In" between because somewhere someone told me "in between" should only be used for physical items otherwise it's kind of redundant.... and it haunts me now. 3. Instead of "Jamie would sit" try "she sat" for more immediacy, plus you've already used her name once.(again a problem I have)
Third line: "watched the agents' icons blink" for more immediacy. (believe me, I'm struggling with this right now myself so it's like at the front of my brain.) I'd consider starting a new paragraph at "Seven months ago" because it really (to me) solidifies that loss of freedom. Also in the line of "seven months ago" how about "she was" instead of "she had been."
I don't understand "If she wasn't free, she should still be trapped behind the Halliwell mirrors." but I don't know what comes before this so that probably changes the meaning. right now, to me, the sentence doesn't make sense. (but it is 11 and I've been up since 5 am)
So if you actually like what I've suggested it would read:
"I want to be useful," she sighed. Over the last year, Jamie had lost the man she loved, her hearing, the use of her arms, and her leg. Between her therapy sessions, she sat at the computer watching the agents' icons blink across the screen.
Seven months ago she was one of those icons. Losing the right to go into the field was like losing her freedom. If she wasn't free, she should still be trapped behind the Halliwell mirrors. A tear ran down her cheek. "I don't want to be forgotten."