It's never too late to email and reach out to introduce yourself. I would make the email have 1-2 follow up questions rather than a generic thank you message. That way you could continue the conversation (and remain in their consciousness).
Also don't say you met them two weeks ago in the email, just say, I really appreciate you taking the time to meet with me recently. After visiting the campus I'm more than ever interested in this program and have two follow up questions from our meeting....