Very slow puberty, should I be worried? My penis and testicles haven't grown at all

I am a 16 year old male. I am almost 6 ft tall, but I haven't shown very many signs of puberty. I have pubic hairs and armpit hairs, I dont have any facial hair. My voice isn't as squeaky as it was around a year ago but I still sound young. My penis and testis haven't grown at all and have been the same size pretty much my entire life. When I masturbate I produce a clear sticky fluid that shoots out but it is not white. I was also a premature baby, born about 2 months early if that means anything.