Keep in mind that "gaining muscle" doesn't necessarily mean getting bigger. Especially considering the type of exercise you're doing, I wouldn't expect it to make your muscles much bigger, but they may grow heavier/denser. The easiest way I know of to notice changes in body composition is to measure the circumference of your stomach each time you weigh yourself. You can also measure your waist, quads, biceps, chest, and hips, but belly is usually where the biggest changes are seen.
Yesterday was day 7 for me of exercising every day... I'm one third of the way to 21 days, which according to science is when it will become a habit!
I went for a short run instead of doing hill runs before my regular workout, and I kept sugar completely out of my diet. Avocados are my friends... I'm thinking I may ramp up my exercise today, but we'll see how I feel this evening.