What has caused my prominent veins all over my body???

I guess I"d need more data to really give a definitve answer, but such things as lipodystrophy (loss of subcutaneous fat) can make the veins appear more prominent. There are several causes for lipodystrophy including genetics, and infectious (HIV). In addition, conditions such as liver disease, can make the veins more prominent. I'd suggest that you get yourself checked out by your family doctor.