I would say one of two things.
1) it is your imagination and for some reason you are expecting things to change so you are looking into things.
or
2) it is NOT your imagination, you proposed, for some reason it through her for a loop, being engaged is not what she wants and she didnt know how to say no,
Honestly, to me she sounds like someone who is acting like they are feeling smothered. If getting engaged is making her feel smoethered then she isnt ready at all for marriage.
I would set her down and talk to her and ask her to be honest, let her know that you love her and if she isnt ready to be engaged it is ok you can call off the engagament and just continue dating until she is ready..
But she sounds to me like she is feeling like a trapped animal. If it were me and I am reading everything correctly, my nature would be to confront her, tell her I didnt think she was ready, ask for her input on it and if she hesitated at all or did not convice me 100% that she was ready, I would ask for the ring back and put the engagement on hold
Good luck..
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