First off, during the first month, both of you were working? Or
did she recently get a job?
I know you feel tired. She's leaving you hanging. However, she may
be too tired with work to feel/think about Love.
Perhaps you should meet her up one day for tea, and ask her if the
two of you can still be together, would she give you a chance to
know her well. A bit straightforward, but that's what i would do.
(Though success is quite limited). This would answer your own
question.
But it does seem like she's losing her feelings for you. Perhaps if
its possible, fetch her home from work? Or just meet her up once or
twice a week for a chat, since she seems to be unresponsive to
Smses. Meeting up is a much better idea than smsing anyways.
Hope you do well...