Get to the point quickly and efficiently. Apologize, don't explain yourself. Say you would like to postpone things. Tell her it would be great if she could think about whether she is open to that.
As for worrying about making asking for the postponement sound like it is all about you, quit worrying. IT IS ALL ABOUT YOU. Trying to obscure that will get you nowhere.
Just get to the point already.
If you want her to hear any of it, you will make it a matter of a very few short sentences.
