How i masturbate...tell me if this is right

I do not mast**bate in the traditional way of sliding your palm up and down on ur penis. Actually, i dont even take out my penis while doing it.

I do it in my room watching porn on computer. But since i do not have the luxury of being alone at my place everytime i m turned on and wanna mast**bate, i have devised a unique method of mastrubation. It just requires me to be alone in the room, i dont even need to bolt the door.

The method: I dont slide my hand up and down. I dont even hold my penis. I dont take off either my shorts or my briefs. I just press my penis against my scrotum repeatedly from above my shorts using my three fingers. When my penis begins to get hard, i stop for a while until its semi erect or limp. So, most of the time during the act, my penis is either limp or semi erect. When it gets erect, it becomes difficult pressing it, thats why i have to make it limper. The whole act can go for a long while in this way. When i finally ejaculate, i press my penis tightly so that my briefs dont get wet. My penis is not completely erect when i ejaculate, it sometimes is limp even. After completion, i go the washroom and urinate, the blocked smene comes out with the urine. Not alway am i able to stop the semen from wetting my briefs, in fact they get wet most of the time but the extent of wetness (or the amt of semen that comes out in the briefs) varies. I put on the same wet briefs only, i dont change them. After an hour or two, the wetness goes away. And i wash my groin with soap and water the next day.

Now i dont know if this method is unhealthy or not but i have been enjoying myself like this since three years thrice a week (i m 20 right now). And uptil now there havent been any problems although sometimes when i happen to do the stimulation (and not ejaculation) for a long time at repeated intervals in a single day, my penis starts hurting, i msure it happens with everyone. Plz advise me on this. Is this right?