You are sort of being unreasonable if you expect your Daughter to go back to being the person she was.
Even if she stayed living at home with you, and stayed a school student, or whatever she was (eg an employee) when she was last being the person you want her to be, and even if she only spent time with the same friends that she always had whilst continuing to do all the things you want her to, she would still change.
In fact @NewbieoneKinewbie you show in the first paragraph of your OP that you do know and understand that as your DD grows (and as time passes) she will change, to not do so would be a very worrying red flag.
I do understand that you and your DD shared a very close and loving relationship and that you want that back. Imo there is absolutely no reason why you and your DD can't reunite in the very special relationship that you want with her - once I had a child of my own, my DM and I developed a relationship together that was closer and more in harmony than I ever thought was possible, even though she was the only human that I had ever been able to depend upon - no matter what.
But as I see it, if you want that amazingly close bond back, you need to let go of any previously held hopes and aspirations you had for your DD. At the moment your DD has changed her priorities, whether that would have happened spontaneously anyway, or she was encouraged or coerced into doing so, you now have a gorgeous Grandchild, and your DD's and your DGC's well-being and happiness are the only things that should be of any concern to you for now.
Therefore, OP, please accept the status quo as it is at the moment, show your DD - and when possible/necessary your D(SiL) as well - as much support as you can manage. I would also be disappointed about my DD not breastfeeding, but the alternatives these days are brilliant, and do have some massive benefits:
- Your DD's partner can encourage his bond with his DC by bottle feeding said DC, and if either of them tend not to look at their DB while giving them their bottle, then maybe when you are giving your DGC it's bottle, you could say something along the lines of
"I have always loved this early stage of feeding my DC - and now DGrandchild - as it is the best time for just gazing into their eyes and having secret imaginary conversations with them, isn't it? Or is that just me?😂"
- Leading on from the first couple of benefits to them from bottle feeding their Baby, your DD's DPartner can take over feeding him or her during some of the more awkward times, eg during the night "shifts" if DD is missing too many hours of glorious sleep! Or if your DD wasn't feeling well, then her DP would be well versed in how to help.
@NewbieoneKinewbie Your Daughter is still "bright", she can still have the same ambitions and aims, or she can have different ones - maybe her main all consuming ambition will be to raise her DC in the best possible way she can manage, or perhaps it will be to go to a (possibly) local university and get a degree in whatever subject she is passionate about. You can either "fight" her in order to try and manipulate her into doing what you think is best for her, in which case you will probably grow further and further apart, or you can support her, both mentally and physically (if possible), to live the life she chooses for herslf and your beautiful Grandchild. Then hopefully that support from you will also get you both into the close relationship you so long for...