Mandatory to the Mother/daughter relationship as your daughter grows and becomes a woman is to set boundaries. Once you have established boundaries, you can become friends. "Best Friends" even.

It is difficult to get to this point, because moms' always want to "mommy" you and see you as their little baby (I speak from experience as a daughter, and now the friend of my grown 33 year old daughter), they don't want you to get hurt in life.

There is no way around it---it is part of letting go of an old relationship and beginning a new one-one that will last.

Change is inevitable; from the time you started to walk, till the time you began your life on your own, it is natural for your relationship to change. Stand your ground.
Perhaps talk to her about the fact that you are a grown woman now and do not want her to treat you as if you are not. You have your own life now, you'd like to have her in it; but as your friend, not as "mommy".

I wish you both all good things in your new relationship---------theo