I came up with an idea of a character who is born as a witch, but grew up as a warrior.
These are her skills:
One-handed (Blade in the right, magic in the left.)
Heavy Armor (Nordic carved armor for the win.)
Smithing (Fits the warrior idea to make your own armor.)
Enchanting (Witches like stuff with fancy magic flowing through it. )
Destruction (Specialised in frost magic.)

I think that aside from destruction and enchanting, there isn't much shown from a witch.
I counted the perks I would use from the mentioned skills, which is around 50, 55 if I use all smithing perks.

I thought about alchemy (Typically witch.), but I'm not sure if a warrior would put good use to it, it might cost too much perk points aswell.
Conjuration came to my mind aswell, but I don't think that my character would summon demons or undead alot, she'd probably prefer fighting alone. The idea of summoning creatures seems to fit somebody like a Necromancer or a Demoniac more than a witch.

What do you think?

I'd focus on one crafting skill, instead of two and switch the other one out with one of the most iconic "witch" skills in TES: Conjuration. It is sort of a staple of the Witch-Covens to deal with the Daedra, summoning and the like.

I could use conjuration and only focus on atronachs and the novice-master perks. Then it would end up in me having 65 perk points, should do fine, I guess. I can probably reach that level if I will spend time leveling the other magic schools, with magicka enchantments it should be viable for me to do that.