Is this song a rip off?

[Thumpalumpacus]

Yeah, I can hear both songs in your piece, especially "Kryptonite" -- same essential progression, similar vibe, clean, reverb-y guitars with a very siilar rhythm (albeit yours having more filigree).

I'd be uncomfortable with the similarities to 3DD were it my song. The progression itself wouldn't be my main problem -- there are only so many chords progressions -- but when you couple that with a very similar feel, you're going to confuse, if not actually irritate, potential audiences.

[Little lunch]

The chord progression you're using is in a thousand songs and more.
I-IV-V is about as common as you can get.
It's like a cake. There's not a lot of different recipes.
It's the icing and decoration that individualises it.
In you're case I would suggest better use of dynamics, possibly a slightly more complicated drumbeat, different sounding guitar effect and when the singer comes in, try to have something quirky about the melody.
Also, it doesn't hurt to use your sevens and nines here and there, especially in the melody.
That's just my opinion man, I'm not an expert by any means. :-)