Hi, I'm a level 12 Argonian with 170 HP 140 SP and 100 MP and I have level'd up Archery, One-Handed, Two-Handed, Smithing, Speech, Heavy Armor and I plan on leveling up Enchanting, all sneaking skills and Light Armor. But let me get ot the point; I wondered if I could switch to a BattleMage/WarriorMagic user or something. Or is it too late?

Level 12? Not at all. You can do whatever you want.

I wouldn't use so many skills though. Stick to one handed or two handed. Worry about one melee skill and one armor skill at a time.

Not at all.

WOW, these where some quick answers you gave me, I have decided to go with a Battlemage build.

I'd say "a bit too late". I'd better begin anew, now that you're only level 12. If not, either you'd be wasting the perk points you've already spent, or you'd risk converting your character into a "jack of all trades".

Just start incorporating magic in your fights. Take out either one or two handed along with either light or heavy armor. As a battlemage I would do this:

-two handed

-heavy armor

-destruction and/or conjuration

-enchanting (for magic cost reduction)

-smithing

Those right there would be my main skills. If you want to stay with the sneaky skills then I agree with Dovakhan ,you'll be turning into a jack of all trades and will eventually get bored with the character. If you limit yourself to a certain style, then to me thats much mroe fun.

My main character was light-armored, sword & shield warrior when he started to get curious about magic in the early teen levels. He started using it a bit and picked up a few spells, then at lvl 20 he made the long trip to Winterhold and has become a pretty powerful spellsword. I'd say your guy is prime for switching styles.

Yeah definately spend some time at the college to hone your magic skills.