It depends on what you and your group mean by "specialized." The system you propose is likely to give you characters with • and •• rankings in many Skills in their primary category — someone who is Mental Skills primary will know a little about almost everything, rather than a lot about one or two things, because of the ease and benefits of getting that first dot. (Going from -3 to +1 in a skill is a big increase, and the most value for your XP.)
Something that might work to give more focus is to alter the cost of Skill Specialties. You could do as you're doing now, making Specialties cheaper in your primary categories, or use the rules from World of Darkness: Mirrors to encourage people to stack them on the skills where they wish to focus.
I find that players don't spend a lot of time increasing attributes; your best bet there is to limit the degree to which attributes can be raised after character creation — perhaps no more than one or two dots from start. Going from a 1 to a 2 or three should be possible; from a 1 to a 5 stretches credulity.