I don't understand.
Mages can circumvent your restrictions pretty easily, like by taking the improved reflexes spell and a magical tradition where they'll have a beefy drain pool.
@Everyone: What's with there being so many GMs that feel the need to come up with some sort of custom restrictions on character creation? Has it never occurred to you that the present character creation rules are the product of hours of playtesting and game balance exercises? Tweaking character creation, like all other house rules, should be carefully evaluated before you do it. If you can't truthfully answer yes to the following questions you've just made a bad rule (asking if you're being too harsh is a sign that you can't answer yes to at least one of them).
1) Does this rule make the game more fun for the
players?
2) Does this rule make the game less complicated to play?
3) Does this rule reduce the paperwork burden for players/GM?
If those aren't 3 solid yeses, you're making a house-rule mistake.