Yes, there is a direct from Houston to Belize, about 3 hours. You will need another little plane on to San Pedro, Ambergris Caye.
I have been there TWICE now, and LOVE IT. It is affordable, lots to see, great viz and temp, the people are awesome and it is very safe for a woman to go. I went alone.
I am out the door, but I will tell you more later.