Snap out of it. Don't wait until spring. Call her up now and just ask her out for a good time. Don't bring up the past. Start afresh. Do it now. Or let it go.
Her feelings will of course have changed and she may not be as sentimental about it as you. You don't need to read her mind but you need to read your own and understand women better. The truth is you actually don't know if you can win her back or if you really want to win her back. 'If Im not in a relationship with another girl'. That doesn't sound like conviction to me. 'I've found someone that is a better person than my lost love. I'm not officially with her yet.' Confusion and idealism.
It sounds like you're in denial and from her perspective she will not see you as a strong man that is a stable lover and provider. You have never made that happen and are still stalling to this day. It's no wonder she never replied to your email.
I know I'm being harsh but you're in limboland. Love happens or it doesn't. Make it happen or move on with your life.