Husband of a professional letterer here. Stop trying to hand letter. Just don't even try. Commercially, no one wants that shit. Even if it's legible it's still not attractive to the eye. Spend time learn the basics of typography, and get a good grasp on kerning and kemming before you post any portfolio work. Hand letter might of been fucking awesome as recently as the early 90's, but it looks like shit when you have a million good looking fonts to pick from.

As the other poster said, your bubbles should not have the rounded square look you're going for. You also need to be able to do a lot more than speech bubbles. An example of one single speech bubble does nothing to convey what you know as far as lettering goes. Can you letter an actual conversation? Narration? Sound effects? Not to be harsh, but you shouldn't be showing anything to anyone until you have the basics down.

Here's the reality you're facing: Anyone with a BA in graphic design, or anyone with a couple dozen hours invested into Illustrator or even InDesign is going to crush anything you can do. Hand lettering might have a "look" to it, but it's like saying Jackson Pollock has a "look" when you compare him to da Vinci. One is going to be much easier on the eye than the other, and let's be real, one is art while the other is just someone throwing paint at a canvas.

People who want to be letterers have to grasp the same reality as those people that want to be graphic designers: There's a lot about the craft that you don't understand as a novice without professional training. If you don't know how to use Illustrator then you're already ten miles behind those that do. You can have the best handwriting on the planet, but this isn't the 70's. Unless your shit looks perfect and can scale like a traditional font then you better toss aside your dreams of being a hand letterer. I apologize, but at the already low rate of $10 or less per page, a letterer is far undervalued compared to all but a writer. If you don't know how to work in Illustrator then no one is going to pay you a single cent.