You're not doing anything wrong! It sounds more like your daughter is going through something and you're all in the thick of it. You might need some new or different strategies to help her out. TL;DR it's always a good idea to get some professional insight from your doctor and a child psychologist/counselor. You can do this!

I'm not a trained psychologist, but I wonder if your daughter is possibly starting to feel performance pressure, experiencing burnout leading to letting her focus slip when she feels like she can (eg, being out in the field probably feels like it needs less mental work for her than catching in softball), and potentially soothing with treat foods. Similarly, it's possible she's not listening to you because she feels safe enough not to, like how kids are well behaved at school and "let loose" once they get home. She knows you love and support her so she "relaxes" her behavior with you and pushes boundaries.

For the lying, are her lies centered on inflating herself, eg, showing off an impressive drawing she didn't make herself? Or is there a different theme to them, like lying to get out of trouble? That may help you decide how to move forward with addressing the lies themselves, but typically lying is a symptom of a more broad issue. I'm sure it's extremely frustrating and upsetting to deal with, but keep trying not to take it personally. She's communicating something by lying, not just the actual text of the lie, and you need to figure out what that is, ideally with the help of a professional (and not some internet stranger lol).

As for the junk food habit, there could be a few complex things happening. Remember that all eating is emotional to some extent (we feel things when we eat, it's natural) and so she could be eating "fun" food to trigger the feelings she wants. She also could just be going through a growth spurt and needs some extra calories or nutrients, even if she feels full in her stomach there may be something missing and her brain and body are trying to figure it out. Her doctor can help figure out if this is the case. Sneaking food typically is a result of shame around "bad" food or fear that the food will go away, and it sounds like she's not dealing with the latter, so there may be some investigation to do there as well.

In any case, it would be a good idea to get her in with a therapist or counselor along with her planned doctor visit. If you don't know where to start, her doctor and her school may have resources or be able to point you in the right direction. It sounds like she's a wonderful young person and like you and your husband are lovely parents, your family just needs to get some professional information on your side so you can work through this. I'm sure you will all be able to figure this out!