... have been using the Canon550D all along. I love it

Well take it from me, if you like using a 550D, you'll probably hate using a much bigger and heavier 5D2 (and bigger and heavier lenses will be needed as well).

There is nothing you apparently need that a 550D (or a similar newer model) can't do that a 5D2 will.

and have recently purchased a 1.4 lens which makes my photos even better.

Ah the first sign of the real problem ... not including photographer skill in the equation.

Your photos don't get better because of a lens. They get better because you know how to use it and how to compose a shot, frame a shot and use light.

Concentrate on this.

However, with my camera being really old and wanting my work to look better and more professional

The way it works is simple : if you have the skills your photos will look professional if you shoot them with any half decent camera. If you don't, then no amount of new camera body or lens will make them better.

You're making a classic mistake : associating "better photos" with "better equipment". It's all about skills, composition, framing and light.

My experience with people saying the things you are is that what they really need is to take more interest in the composition, framing and lighting of shots. This is harder to do because there's no quick fix, but it pays off.