I'm ana-positive; could I have lupus without any symptoms?

See a Rheumatologist. This really needs to be discussed with a rheumatologist who can take a complete history and do a physical exam. In addition he or she will need to do additional laboratory tests before making the diagnosis of lupus or ruling it out.
Yes. Many diseases other than lupus and many healthy people have positive anas. You can also have lupus without having any symptoms and you can have a positive ANA for years before getting systemic lupus erythematosus. Most likely, someone with no symptoms and a positive ANA does not have lupus.