My 10 year old yorkie is very boney and skinny, I can feel every bone in her 7 lb. body.
Her stomach also feels bloated and tight.
She eats and drinks normally and there is no worms in her poop.
I am taking her to the vet, but was hoping for someone here to ease my fears of it being worse than I thought. Thanks forum!

Unfortunately there are a lot of things that can cause weight loss so I can't give you an answer.
You vet will hopefully do bloodwork which should give you a cause.

How long has she been losing weight for?
Has it happened all of a sudden or gradually over time?

Is she eating and drinking fine?
Still active or lethargic?

Just because you don't see worms in the stool doesn't nesessarily mean she doesn't have them. There is so many possibilities, taking her to your vet is the best option.