What Causes Wetness At The Nipples When The Breasts Are Stimulated?

Did I lactate? I am a 19 year old male and I sometimes stimulate my breasts/nipples because it feels good. Recently I ve noticed that I ve grown small breasts that feel a lot fuller than when I just had a regular chest and when I stimulate my nipples they get wet but there is no visible fluid. What is this wetness I m experiencing? Will my breasts continue to grow if I keep stimulating them and will I lactate if I haven t already? Should I stop playing with them if I don t want to lactate?