Personally I'd go only 4 shield, and 3 IF, then you could have 6 WM
This is my 30 build
Level 30:
18/18
2 SKills to attributes
1IF
6 PS
4 Shield
6 Athletics
6 Riding
6 WM
WPF:
119 1h
119 polearms
At level 33 I'm going 21/18 not 18/21, but if I were doing what you want to do, I'd suggest this:
Level 33 (35 569 612 xp)
Strength: 18
Agility: 21
Hit points: 57
Skills to attributes: 2
Ironflesh: 2
Power Strike: 6
Shield: 4
Athletics: 7
Riding: 7
Weapon Master: 6
Change around your IF and WM all you want, but I'd prefer to have WM over IF myself (I like faster/more damage on my melee weapons). And you really don't need 5 shield on horseback. The 4 shields are the best, 6 would be decent for some strat battles, but for c-rpg, 4 is all you need in shield (get elite cav shield or knightly heater shield).
My 21/18 build at level 33:
Level 33 (35 569 612 xp)
Strength: 21
Agility: 18
Hit points: 62
Skills to attributes: 2
Ironflesh: 3
Power Strike: 7
Shield: 4
Athletics: 6
Riding: 6
Weapon Master: 6
119 1h
123 Polearms