In a lot of my dreams over the past 3 weeks, I've been remembering making concious decisions in my dreams. Does that mean the dream was lucid, or was it just extremely vivid?
If you want to know whether these vivid dreams were lucid dreams, I suggest you look up the definition of lucid dream on wikipedia and compare it doesn't really matter though, as you probably know it could be done "more lucid", and no matter what it's called, it's still the same thing that happened. I might have misunderstood this question though :/

Do I have to do an induction technique to actually become lucid?

And what induction technique do you suggest?
No. After all, there are people who have lucid dreams without even knowing that such a thing exists. Techniques increase the probability of having one though just browse this site and read up a bit about WILD, DILD, WBTB etc and choose the technique that suits you the most (as some might not fit your lifestyle or sleeping habits). Most of the ILD-techniques are simply principles though, instead of detailed procedures, so you might make up your own technique based on these principles (all I ask of you is that you don't give it another ILD-name and try to establish it in the lucid dreaming-community lol).

I'm sorry I can't answer the remaining question as I haven't had a lucid dream myself yet (at least none that lasted longer than ~1 second).

Good luck getting lucid.