Okie

I have been growing for about 3 years now and the only problem I have is airy and loose buds . I grow in coco I grow with HPS and change the light every 6 months. Summer time my high temps in my grow cabinet is around 80 to 84 deg. Winter it stays around 75deg. I feed General hydroponics Trio and feed them every time I water with plenty of runoff. I have good airflow with a 6" exhaust fan . And have 2 small fans to circulate air within the cabinet . And I buy seeds from Nirvana. What the hell am I doing wrong? Please help