Your 4 year old daughter won't think any of that you mentioned, "not smart enough, low confidence" all that comes from the parents and what they see of their child. Be present with her and encourage her to continue speaking up for herself. Get her involved with arts and crafts at home and educate her on effective communication like asking questions if she doesn't know, saying please and thank you, greeting friends with a wave or hello. Looks fkr ways to improve her skills at home so when shes in school shes well adept. I think the most important step is making sure you stay positive around her continue to guide her to greater independence as she grows up. I assure you all she cares about is mom and dad being by her side. If her teacher has made comments about her lack of progress then maybe holding her back a year would benefit her but theres no way for us to know any of this. Developing her communication skills now is essential to her overall wellness later in life. We all want to protect out children but sometimes the best solution is tossing them into the wolves and letting them find their way out with some guidance whenever they look for it. She might not ask for help all of the time but you being present, positive, and persistent will boost her happiness and I think you'll see improvements. It's demanding but it's all for you daughter. From my experience as a life time stutter, my most crucial years came around the age of 10. Thats when you'll want to really step up the encouragement and support for self advocacy. Grow and learn with your daughter and develop her interests as they come. Hope even a skosh of this helps you and your daughter :)