That quick release want to be tight! When you brake hard, that caliper is trying to stop the edge of the disc which is traveling up. Physics and all that - also trying to force the hub down; out of your dropouts. That force, because of leverage, is far higher than your weight; the only thing besides your quick release holding your front wheel in place.

There are two things you can do for both more security and ease of use. 1) Don't line up the lever with your fork. Rotate it a little clockwise so it points to about the saddle. Then you can get all your fingers behind all of the lever. (Feel free to fin e tune the "point" to where works best for you. But keep it pointed roughly back so if it ever gets tangled with anything, it won't open.) And 2) get a better quick release. You see how your QR is aluminum, symmetrical and you can see the two cams on either side of the lever? All bad. The good skewers are steel (well the lever only can be aluminum on a racing quality QR), have just one steel cam inside the head of the skewer, completely out of sight, and the lever comes out the side of the head and takes a right angle turn. These good levers generate far more clamping force with less effort and are far more secure. Common, cheap Shimano QRs are what you want. Any bike shop. (On your bike, the front is the only one that you need. The rear disc brake is in front of the hub, trying to force the hub more solidly up into the dropout. Any old QR will work there.)

Don't worry about the QR squeezing your frame and fork. Both are made to be about a mm wider than the hub to make putting the wheel in easy. That tiny squeeze in, while you can see it, won't hurt anything at all.

Ben