Here is a page to help. This address is for a chart that is well down the page but the whole page is useful. It is written for doctors so you may have to do other reading to support your understanding of it.
I used the chart for self diagnosis when I got no other help. I suggest printing the chart and marking out the things that obviously do not apply to your condition.
That chart indicates that Paramyotonia tends to have very mild weakness associated with it, so that seems to imply that Hyperkalemic Periodic Paralysis is more likely because of my severe weakness. I've heard the two conditions can co-occur, though, and wonder how that presents itself.