Thanks for the candid report.
Sometimes the best motto is, "When In Doubt, Don't Go Out".
I face this type of decision many times when I go down to the ocean here in New Jersey. I'm "chicken" enough to walk away from dubious situations... most of the time. The hazard is pushing our confidence levels too high.
By the way, are you aware of the "Swim It" device, which is a rip-cord triggered life vest that is worn strapped around your thigh while swimming?
Provides a bit of safety back up when you're out there alone.... (check the internet)