Oh - I forgot to mention - if you get a very good cut and some highlights, the damage caused by the highlights will actually give your hair more body and volume.
Highlighting causes the hair folicle to become rough as the cuticle lifts from the shaft - these lifted cuticles basically make each hair folicle fatter. Now, this won’t yeild good results if you wear your hair long, or don’t have a good haircut, but a good cut and colour can do wonders.
BTW - I’m just going to jump right in here and say you’ll probably be happier if you work with what you’ve got, rather than trying to massage it into something else. Very long hair only works for certain hair types, and thin fine hair is not one of them.