I feel like I don't know her the way I always had. The person I knew growing up and who I could tell my inner most secrets to is not the person she is today
Op, I could be your Mother (though maybe not as interesting

) Many mothers reflect on what their role should be when their children are adults. Many mothers decide that since their children are independent, the relationship can now be more of a peer. A peer relationship. OP, your statement above does not match this reality. You'd like to still have a Mommy. Some woman continue more in a Mommy role, being the Matriarch, insisting on a lead role, keeping power over the younger generation, and the younger generation gets some comfort that all is well, that Mommy is there to fix things . This is not your Mother. Be grateful for the good thing re: how she sees her role, but it's not this.
Here's how you approach the new reality: do, act and speak as if she were a friend. If you wouldn't say it to a friend, don't say it to your Mom. Support each other, but know that it's not a one-way street. She does not need to take care of you anymore than you need to take care of her. No hurting her feelings if you wouldn't want that yourself. This is an equal relationship ... at least approach it that way. Start from the point and you're a whole lot more likely to develop a meaningful, mature relationship.