Dear skyblue:
You wrote: “one plan I could think of is, to stop contacting her for a month and confess (as her to date me) in my birthday next month”.
My suggestion, another plan you can consider, is to tell her any time, soon, how you feel. If you don’t want to sound too heavy, tell her how you feel in a casual way, a casual tone of voice. You can encourage her to share with you how she feels, point to her distant behavior and ask her what she feels.
If she is able to tell you how she feels, if she feels comfortable doing that, not fearing that you will get upset or angry, that will make her feel closer to you. There is nothing much that makes a person feel close to another than the comfort in sharing honestly what one feels.
And not just once, but ongoing.
anita