Frustrated when visiting family...help!

My new lifestyle and weight loss has made me a much happier, healthier person. I live by myself and have good control over what I purchase at the grocery store, trying not to shop while I am hungry. Being single and living with my dog, I often travel to see my parents and spend the weekend with them. My sister moved in next door to them recently so it’s nice to see them all at once. Lately though, I’ve really started to notice how different my “new” life is to theirs and how judgmental they can be. I don’t force my way of living on them in anyway, but if I want to be conscious about what I eat and ensure that there aren’t any hidden calories or ingredients that I am unable to tolerate (I’m the only one in my family that is lactose intolerant and I feel they haven’t taken the time to fully listen to me and understand that a pill doesn’t make it all better). Therefore, I’ve offered to cook the meals while I am staying with them, which they appreciate. Here’s my problem- I don’t make double or triple the recipe like my mom usually does so none of us can be tempted by second or third helpings. I’m not trying to monitor their eating or calorie intake, but they are always saying how they need to lose weight. Yet my dad can consume the rest of the recipe in the blink of an eye and add half the salt shaker to his plate before even tasting the food. In addition, I accompany my mom to the grocery store and this last trip she bought baked goods from the bakery counter. A chocolate éclair for me (I had mentioned how good it looked), a whoopee pie for herself, a red velvet cupcake for my sister and an overloaded cookie for my dad. I feel like she is enabling everyone to be overweight and tempting them with unwanted calories. I didn’t touch the éclair or any of the other treats. When I had mentioned that the cookie had to be about my daily calorie intake for the entire day, my sister about bit my head off. My dad could stand to lose about 100 lbs., my sister about 60 lbs. I feel my mom is fine, just needs to eat healthier. Again, to each their own lifestyle, but it’s so hard to want to go visit them without being frustrated at them and feeling like I’m constantly being scrutinized for how I’m living my life. (My mom is proud of the weight that I’ve lost, but constantly reminds me that she thinks I’m over doing it). One more thing to mention is that I am going on a small trip with my mom for our birthdays in a few weeks. I still plan to track my calories and work out a little at least every day. I know it’s going to be tough enough to do just that, but I know my mom will say something and complain that I’m on vacation and need to take a break. Any suggestions on how I can make this situation better and can have future visits less frustrating?