That breaker is what we call a "double-stuff" -- it is designed to fit 2 breakers where one normally goes.
Your panel is in the GE Q Line. They do double-stuffs a little bit differently. But the same basic concept applies, you have 1" wide spaces, and each space only has access to one pole of 120V. For more on how spaces work, read my Q&A on "what is a double-stuff breaker". In particular, note what a quadplex breaker is.
GE does not do duplex/quadplex. They offer individual 1/2" wide breakers and you sandwich them together into "build your own double-stuffs". If you want a duplex 15/20, you just build it. I believe you see this setup in row 3.
Now as far as quadplex breakers, they have the 240V breaker you have right there. Similar to a quadplex, you mount that thing straddling 2 adjacent spaces, so it is grabbing a bus stab from each. That leaves 1/2 space empty above and below. You fill those with 1/2 space wide breakers: Essentially, it's a "build your own quadplex" :)
You are trying to install it on an even space, in row 1, instead of straddling 2 spaces. I would expect the breaker to be keyed so that is impossible, so I don't know how you forced it in. If you damaged or altered the breaker, throw it out and get another.
My best advice is to move the breaker in row 2 up to row 1, and pull out the 1/2" breakers in row 3 out. Split them apart, stick this new breaker in the middle of them, and put all that back into rows 2 and 3.