What breed is my cat?

So we found this little black kitten on the side of the road 2 years ago. She is black with a few white hairs on her chest, large vibrant yellow eyes, a VERY sleek and glossy black coat, very graceful figure with an arched back, is extremely petite (she weighs less than 9lbs) she has a very thin and elegant figure. She also has the 'snake like' head structure. She is very playful but prefers to be independent vs playing with others. She gets along well with her sister (a stray brown tabby) but does not share toys with her (even though they grew up together). She incredibly shy around new people and hides until they leave. She is sweet but does not cuddle much and prefers to sit on her own. She is moderatly vocal. I know most people are going to say shes just a regular old domestic cat but there is something so graceful and elegant about her that makes us think she might be some kind of specific breed. Any help?