Formula weaning at 9 months?

Ok. So, my LO has never been a formula lover, particularly after introducing solids, still she was drinking 8oz bottle 3 times a day along solids. One week ago, out of the blue, she started to refuse bottle all together. She will not accept it even before bed. She pushes bottle away with hands and cries if we continue to offer. She does not even want to drink water from the bottle, she takes water from cup. So, we tried to give her milk from a cup, she took a sip a split it away. We tried decreasing solids and water, yet she did not accept formula, was sucking her thumb desperately, because she was hungry. I do use a bit of formula in her morning careal, but that's it. Have you had something similar happen? I don't know what to do. Shall I just accept the fact she is weaning? Or shall I try smth? Any recommendation? Anyone? She just turned 9 months old on June 2.