I just turn 34. I have my first boy at the age of 29y (2013) and my second boy at the age of 30y (2014). We're now trying for a girl. Anyone ever try Chinese Baby Calendar? Or any tips or what so ever to have a girl in my age?

34 is not a bad age to conceive. Eat good food, exercise regularly, stay away from tobacco and alcohol, and start taking prenatal vitamins. As far as the Chinese calendar goes, I am not an expert. However, I believe it is more observational than scientific.