Re: 9 month old suddenly spitting up/vomiting
This is a tough one to answer with certainty. The one thing you can be sure of is that the vomitting is not being caused by your milk. Returning ovulation, the things you're eating- they aren't going to cause baby to throw up. It could be that the baby food is causing your LO to be sick to her stomach- what are you offering her? And it could also be a tummy bug, because a sick baby isn't necessarily going to puke every day. Does she seem unwell aside from the throw-ups?
A little weight loss in an older baby isn't so concerning. Older babies who are becoming very mobile (crawling, cruising, standing, etc.) often slide down the percentiles as they devote increasing amounts of calories to motion instead of packing them on as fat.
I know your LO has been a challenge to nurse, but I wouldn't worry too much about any of this.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"