Bread-Bakers v100.n011.27

the few recipes I've used for sourdough have included the starter recipe...I
already have a starter (part from about 4 or 5 years ago, with the King 
Arthur starter thrown in for good measure). How do I know if my starter is 
as potent as the starter they give the recipe for? I made sourdough bread 
earlier this week, the taste was tangy but it didn't rise very high & the 
texture was sort of cake like (I used the Bernard Clayton recipe).

thanks for any help you can give me.
Robin