You are right. Most, or I can say at least 90% of slaves came from west Africa, and from what is now Angola area. Majority of slaves actually came from the port of Calabar, in what is Nigeria, and included Igbos(Ibo), Yoruba, and some came from what is now Ghana, all the way to the tip of present day Gambia.
I'm of Nigerian origin (both parents are), and I'm a product of both the Nigerian society and the American society. I've a lot of Caribbean friends and have noticed the strong similarity in regards to culture, and I still find it amazing. It might have been the way slavery was handled in the Caribbean, allowing the slaves more control of their life, and thus they were able to retain more of their culture.