I have tried developing longer, but at the time there were to many variables which i wasn't attempting to control, so what i did get was that the darks were too dense when enlarging, and the highlights were blown out. Now i understand that this is due to my underexposing negatives when photographing, hence, my compensation during photographing.

If i develop for longer, will my highlights blow out? or will i just get more shadow detail?

edit: i ask because if i gain contrast from losing highlight detail, i'd rather just keep as i am.