Slooowest HP development ever!

[Peter_20]

I kinda liked that Paladin/Black Mage/Fighter party suggestion, so yesterday, I started a new game with that party, and it rocks.
However, I'm having problem with Maria's HP development, because it sucks.
For some reason, it increases veeery slowly, in fact so slowly that it's downright ridiculous: 1-2 HP per HP Level.

What's going on?
She started at her usual 20, and by the next Level she increased to the super-impressive (NOT!) 21, followed by 23 and 26.
Damn, the other guys increase a lot more every SINGLE level!

P.S.
I don't know if this is of any importance, but perhaps you'll understand my situation better if I add this info:

DESTINATION: Snow Cave (Minh recently left my party, Josef will join soon)

MARIA'S CURRENT STATS:
JOB: Hunter/Black Mage

HP: 26 (#¤&/%#!!!)
MP: 54

Pwr: 8
Agl: 15
Vit: 4
Int: 31
Soul: 10
Def: 2

Attack: 9
Hit%: 2-48%
Evad: 1-07%
M.Pwr: 13
MDef: 1-23%

EQUIPMENT:
R. Hand: Long Bow
L. Hand: -
Body: Clothes
Head: -
Wrist: Leather

EQUIPMENT PROFIENCY:
Fist: 1-00
Shield: 1-00
Knife: 1-00
Cane: 1-00
Spear: 1-00
Sword: 1-00
Axe: 1-00
Bow: 2-42
D.S.

MAGIC:
Fire: 2-24
Ice: 2-15
Bolt: 2-08
Slep: 1-00
Bsrk: 1-00