How to request to be co-corresponding author
While I don't really understand the value of this to you, not being in your immediate culture, the solution is clear as it is in most similar situations. 

If you want something, just ask for it. Give her your reasons why it is important to you and why you need this at this time. If you ask it as a favor and not as a demand you might be more likely to prevail. 

You may not be successful, but nothing you do can guarantee success. Asking keeps it collegial and preserves your relationship for the future. 

Yes, you contributed, but so did she, I assume. In most places corresponding author is just a task, not an honor. 

I'll suggest that whatever happens in the handling of a single publication it is unlikely to have much of an effect on your career. Working for long-term relationships is, to me, much more important than any check mark on a box or minor point on a CV.