I have a couple of suggestions for you...
Liveaboard, Jan-Feb...
check out the Nekton St. Croix itinerary.
Nekton Diving Cruises - Comfort, Stability, Worldclass Diving
fun boat with a fun crew, very stable boat = seasickness is minor if at all on their boats due to design. We have done 2 trips on Nekton boats and loved them. Fly into San Juan, Puerto Rico.
Explorer Ventures: Adventures in Live-Aboard Diving boats get good reviews. Not quite as stable (anti-seasickness) as the Nekton boats but still great. They have boats in Bahamas, T&C, and Saba that would meet your needs.
The swells you experienced in NC diving are not the norm for liveaboard diving. The boats are usually moored in areas away from any "weather". Also, you can dive as much as you want or as little. On our last Nekton trip we had several couples where the wives only did 2 dives per day but the husbands buddied up and did 4-5. No big deal. I did 4 dives per day and sat out a couple of night dives, my hubby did them all. We never got bored. If you can do nitrox, do it... we truly feel it makes you have more energy diving day after day.
Other options: Jan-Feb can be iffy weather at many locations around the Caribbean. I would check out Roatan, Utila, Curacao, and Bonaire. The first two are the least expensive choices. Good-great diving at all.