No, I don't think they're throttling you. It sounds about like the right speeds. I'm on a 30Mbps plan with my provider
P.S. In case you wondered what the abbreviations are, here’s a quick list:
Megabyte = MB
Megabit = Mb
By extension, speeds would be measured as such:
Megabytes Per Second = MBps (if this was the way it was actually measured)
Megabits Per Second = Mbps