Consult your dad that you're interested in guys and that you're not his 'little' girl anymore.
Just explain you're after nothing serious, but there's a couple of guys you like at school. (Even if there isn't).
Or plain don't tell him.

It's not weird you haven't had a boyfriend yet, it's just your choosing. If you aren't flirty you won't grab attention easily, and just because you're shy and have some acne that should let you hold yourself back.
If you can hang with mates, with guy mates and mingle that way it's a good start.
But if you're uncomfortable being outgoing, just work up slowly with it, just go out with your best mates.. and then slowly build up more and more people you don't know to come out with you.
Well eventually you'll know them more the first time you meet them. But if you catch the idea, you just got to build at your confidence.

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"As long as there's free will, idiots will never learn"