Feeling depressed today

I'm feeling super depressed today. Like I'm affecting my baby due to being unhealthy before being pregnant. Yesterday my anatomy scan didnt go as planned I think due to my weight. I've been constipated for days also I think due to my diet and limited exercise. I just feel like I'm going to mess her up somehow and it's going to affect her in some way. I've been stressing way to much lately over just her. Nothing is wrong at work or home it's just these kinds of things. I dont even look pregnant at 21 weeks. Just feeling sad overall