I read this book somewhere between 1997 and 2002; found it in my high school library. The main character was a girl named Summer (I’m pretty sure), but I don’t remember much about the early story. She falls in love with a dragon somewhere along the way, and carries a dragon egg in her bellybutton, I think? And maybe the dragon dies?
Could this be The Unlikely Ones by Mary Brown?
The Ring's the thing...
Thing was a young girl who hid beneath a mask. Her companions included a crow, a toad, a goldfish, and a kitten. Never had a more unlikely band of unheroic heroes set off on a difficult and dangerous quest. But Thing had a ring with unusual powers...
Summer was an orphan who only wanted to find a husband and settle down. But first she had to help out a blind knight with amnesia and a winged pig. But how to get those two, as well as a raggle-tail assortment of other creatures in distress, to the far-distant place where they belonged? Summer owned almost nothing except a certain magic ring...
Sophie was cast adrift in London by the untimely death of her parents. Then an uncle left her a legacy that would lift her up from poverty if she took a dragon's egg into uncharted Asia
Summer's 'magic ring' is a red gem that she wears in her navel. It doesn't give her any significant powers, but it does mean that she doesn't age.
The series is actually called "Pigs Don't Fly", which is also the name of the second book, in which Summer appears. https://www.fantasticfiction.com/b/mary-brown/pigs-dont-fly/
The Unexpected Dragon (1999) by Mary Brown is the book the OP is looking for.
Includes "Pigs Don't Fly", "Master of Many Treasures", and "Dragonne's Eg".
It is the Pigs Don't Fly series, it looks like, but The Unexpected Dragon seems to have compiled books 2-4 together, and left The Unlikely Ones on its own. This was confusing for me as well, as I owned it, but never knew it was a series pushed together into a single book or had another book to add on to the beginning!