I think the problem lies in the fact that all you can play is the first chapter. Outside of the last fights, there's not really much access you have to source point skills seeing as you just get the collars off at the end.
You can get one collar off in the fort or could leave the fort immediately, get all your collars off (at level 3) and play the game in that order. You need to be level 4 to buy any source skills though.
There are plenty of source points to be had. 15 from source vampirism and 2 from each puddle if you bless them. I guess you could run out but you'd have to try...
