Is anyone else finding this stage with their little one really challenging?

I’m feeling completely lost at the moment and just hoping someone out there can relate. My daughter has just reached 9 months corrected (she turned 1 in April but was born early), and up until now, she’s been the calmest, happiest baby. She rarely cried — even as a newborn. And by “newborn,” I mean since we brought her home from the hospital last August after her NICU stay. She was always so content, rarely fussed, and just seemed so easygoing. But something seems to have shifted around the 8 to 9-month mark. Almost overnight, her mood and behaviour changed drastically. She now cries over the smallest things — like if I open a packet for her, she’ll suddenly burst into tears because she wanted to do it, or maybe just didn’t want me to touch it at all. She doesn’t seem to want my help with anything anymore, gets upset when I try to comfort her, and often just wants to be left alone. She’s also refusing to eat or drink properly, and no matter what I try, it feels like I can’t get it right. It’s heartbreaking and exhausting. I even took her to the doctor because this is all so unfamiliar to me. I’m a first-time mum, and this dramatic shift caught me completely off guard — like being hit by a ton of bricks. The doctor said everything seems fine physically, which is reassuring, but also left me feeling even more lost because I still don’t know how to help her or what’s going on. Maybe it’s a developmental leap or separation anxiety or something else I’m not seeing… but I guess I’m just struggling to find my footing in this new phase. Especially with her being a preemie, I’m always trying to balance her corrected vs. actual age, and it sometimes feels like I don’t know what’s typical for where she’s at. If anyone’s been through something similar, I’d really appreciate hearing from you — I could use some reassurance or guidance right now.