It sure doesn't sound like you overfertilized them. More likely is the size of the pot problem as they can quickly become root-bound. How big is the pot?

Also what potting mix did you use? Does it drain well? Root rot from excess water retention in the mix or from overwatering is another possibility. What is the leaf color? A good rich green or pale or yellowing?

And what have your temps been? The too can affect blooming and fruit set. Is it getting plenty of sun? Overly shaded plants are poor producers.

More info please? ;)

Dave