My daughter turned 14 in feb 2007. In march 2007 she got her very first period. It was a pretty heavy one and she has not had another period since! It is now sept (6 months later!) Should I be concerned or be patient and just let nature take its course?

Mm let nature take its course-I think she may be irregular-how about yourself at her age? If you were similar then it makes sense, otherwise I'd check the BMI of your daugter, her weight will influence her menstral cycle.

Is she concerned?

It's normal for the cycle to be irregular at the beginning. But if you are concerned consult a doctor

It could very well take 6 months or more for her to have another cycle. Irregularity is common in girls so young. It takes approximately 2 years for a cycle to become normal and regular.