Sometimes a student comes to my class a couple of times and then asks me about whether I can recommend a more difficult or vigorous class. I teach very gentle classes and sometimes students want something that pushes them or challenges them in a very physical way. I always encourage them to try other classes around town -- I would encourage anyone to do the same. It's important to remember that there are lots of different styles of yoga and that what feels "right" for your body on one day or during a certain period of your life, may feel not so "right" at other points. Personally I think it's great to explore all kinds of yoga -- although I would always make sure that the teachers are well educated and knowledgeable and encouraging. For a good overview of some of the types of yoga practiced in the US check out this Yoga Journal article; for a list of qualified teachers take a look at the Yoga Alliance web site.
Happy Practicing and Happy March!!!