You would need to look up your modem, and find out where you can access the signal levels.
Most modems I've known, use the address »
192.168.100.1From that page, you should be able to navigate to a page, showing your signal levels.
As for the speed test site. You can pick other servers on the speedtest.net site. None are closer to you? None provide different results?
If you test there often, is your ping always in the 60s? Higher? Lower? The latency could be a result of other issues, unless thats normal for that test site.