its got good healthy roots

it has grown about a foot in about 3-4 months. I just think it looks funny. It could be thicker. I understand we cant totally change how a plant heals/grows but we can alter it and make it better.

You should probably cut the skinny growth at the base and root it, let the bigger bottom section generate new pups that can be grown thicker with proper watering and feeding with a cactus fertilizer.

1)You can cut the top off, as suggested, if you want, and that would most likely stimulate new growth at that point in the form of an appendage or two. Rooting the top part will create another plant that looks similar to the one you have, so you may want to just toss the top.
2)You could just leave it as is. The skinny part is from a lack of light and won't fatten up to match the rest of the plant. It will always look a bit weird, but that's what gives it character!

Mine has a little nubbin growing at the top where the plant was either damaged or purposely cut before I bought it and I have a pup growing from the base.

Good luck with whatever you decide.

Nancy