Welcome to the forum and thank you for sharing your story.
With HR background, I may have some advice for you:
1. It is very challenge to have a full-time job and take care of two kids at the same time. Everyone has limited energy everyday, it is easier for you to get exhausted and to have your stress escalated. You need to make your life balanced and sustainable. Are you really able to handle this full time job for long term or it's better to discuss with your manager about reducing your work hours? Are you able to make yourself healthy meal and have good sleep? Do you have a period of time in a day that belongs only to you for reading, exercise, meditation or have a chat with a friend? You need to find time to think about these questions.
2. From your description I feel your team is lack of leadership. What you can do as a member of the team, is to make your leader easier to lead and easier to reach the team target. If you feel hard to impact other team members, it's ok and it's not your duty. At least you can actively match with your leader about your role and your focus. You can also find a good timing to talk to her about your feeling, when both of you have good mood, and be constructive.
3. You expressed your feeling to one of your colleague, don't feel sorry for that because emotionally and psychologically you have such need. You can't just hide this in your heart otherwise it'll get escalated. Try to talk to a close friend out of your organization, or your family, you need a listener, just to choose the right one.
4. Are you a person hard to say No? Sometimes it's necessary, just to express in a right way. Don't put too much on your shoulder, focus on most important tasks of your own, then your position responsibilities. If you can make extra contribution to your team that's good, but again, match with your manager first, and make yourself balanced and sustainable.