chemistry is a sign it's your soulmate -- though chemistry alone is not
There are ways to know if there's chemistry pretty quickly -- I detail this in the video (the last of my summer teaching tour videos -- shot on a boat near a glacier in Alaska)
If you are in doubt about the attraction between you and someone you're seeing, this will help you out.
Make SURE you include chemistry prominently on the list of things you're looking for in your mate. The other one I always ask people to add is "available" -- a whole other subject.
Enjoy, and let's connect again soon!