@petergarida,
You are way too slow, and you are missing out on opportunities.
Waiting 15 days to make a move? What do you need, an engraved invitation?
If she is not dating someone, ask her out. If she isn't, then don't. And don't hang around and pine. See other people and live your life. If you are both unattached at the same time, then try again. Don't wait over 2 weeks and make a big production out of it.