You get 3+your int modifier spells at first level. Take the odd numbers off the dex and Wis and put the points you free up into strength and Cha. WotW is a very RP-intensive adventure and some social competence will help.
I don't think you necessarily need CON at 14. Maybe if you didn't have a penalty to it, but you're spending 10build points on that. If you're worried about survival, you can take a toad as a familiar, which gives you an extra 3 HP, and put the points in a bit more Cha.
You get 3 +your INT mod.
Those seem like some rather weak 1st level spells.
Burning Hands, Cause Fear, Charm Person, Enlarge Person, Obscuring Mist, Web Bolt all seem like better choices than Ear Piercing Scream or Frostbite.
I also agree that you don't need to buy a 14 CON as an Elf. 12 is plenty. Unless you specifically need a 15 DEX or 13 WIS for something, you don't want an odd score in those abilities. As a witch all of your level-up attribute bonuses should be going into INT.
STR 7, DEX 16, CON 12, INT 20, WIS 12, CHA 7
That is similar to what you came up with, just a little better.
Why did you choose the Raven as your familiar? The Greensting Scorpion or Compsognathus would get you a +4 to initiative. If you wanted a talking familiar, the Thrush gets you a +3 to diplomacy, which is better than a +3 to appraise.
Ear piercing scream is actually very good because of its daze effect. Frostbite is a touch spell so a little more risky; I like it mozt with Reach metamagic applied.
