If you're looking at babysitting, ask neighbours with young children if they need a babysitter. If you're good and they like you, they will recommend you to friends. (Mothers are always asking each other for recommendations!) It's all about networking.
It will help your cause enormously if you have a first aid certificate and experience. If you have no experience, see if you can volunteer at a child care centre or preschool. If you are good, they will give you a reference too. The higher your qualifications, the more you can charge. What about doing a certificate in child care?
McD and supermarkets are always hiring. But I think you've already applied for those jobs, yes? Honestly, if you can't get a job at one of those places there is something you're doing wrong. And this something could also prevent you from getting babysitting jobs too. You're obviously very literate....but what else could be happening? Have you sought advice from an employment agency?
There is money to be made dog walking. Again, I'd start local and network. What do you know of dog behaviour? If you don't know a lot, I'd volunteer at a local shelter and get to know other dog lovers.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.