Body changes and how to measure my fitness...

Hi, I used to be a cardio junkie like Kelli, with a heavily restricted diet. I have since adopted a much healthier routine and perspective, but I am experiencing some difficulty reconciling changes in my body with the actions I have taken to be more fit. You see, my waist has increased 3 inches since I began lifting weights and building more muscle tone. My diet is the healthiest it's ever been; I bought the FB Meal Plan and honestly didn't need it because I was already doing it. Buying the meal plan just gave me new recipes! My clothes, for the most part, still fit well. There are a couple of dresses I have had to let out around the waist, but otherwise the only major change is this measurement. It makes me feel bad. Now, when I look at clothing online and check size guides, my waist is considered a "large", even though most of the time I need a small or medium. I'm short, too, so I often need petite sizes and I am scared to shop anymore and feel defeated because my ab muscles and slight increase in body fat due to being healthier and not starving myself are putting me in new categories with clothes and driving home this feeling that I am somehow failing or too big. It might sound ridiculous, but I grew up around a lot of unhealthy ideas regarding body image, which was what led to me being unhealthy in the first place. It doesn't help that when I go online and research whether increasing muscle mass can make your waist bigger, I get a slew of blaming articles from fitness websites trying to sell something saying things like, "Weight lifting should never make your waist bigger" and harping on how you have to be diligent in your diet. I only have treats every 7 to 10 days, just as the meal plan suggests and I mean one treat - not a binge-fest. I've eased off doing ab exercises as much because I did find one article that said you can increase waist size by over-focusing on your obliques. I feel really strong and healthy, but even knowing that am still feeling hard on myself, too. I'd appreciate advice and other people's experiences. Maybe not being in my twenties anymore is a factor too? I don't know. Thanks for reading and have a good day.