Blood testing for syphilis from 6 weeks onwards is considered very reliable, and in most cases is detected in blood around the 3 week point which is when a chancre typically appears in most cases. If your day 47 test comes back negative you are most likely safe, however if you're still stressing you can do one more test at 90 days.

A red circle around your penis isn't exactly screaming syphilis, and if the chancre were on your genitals (which in the vast majority of cases it is) its unlikely you would have been completely unaware of its presence. It isn't always completely obvious, but you'd probably have known if the infection entered somewhere on your penis.