I know several people who have had good experiences with online dating, several of them have been married for many years and have started families. At the very least, it helps you kind of relearn how to communicate with men again. But you still have to be very picky and careful with who you talk to, and what you reveal, especially when meeting up.. always meet in a public place, b/c some people are real creepers! I've have heard some scary stories, some people don't reveal their crazy side until you think you really know them.
As for me, I would join groups of things that interest you. On meetup.com there are plenty of groups for single adults. Photography, foodies, movie goers, runners, career groups, hobby groups, religious studies, book clubs... You are in college, you can join a student union or club that is in your field or area of interest. Get to know someone while in their element that has a common interest.
I met my husband at church. Do you have a church group or subscribe to any particular faith or philosophy? That is usually a very good place to meet people with like minded goals and morals.
Just remember to take. it. very. slowly... you are a busy momma, so put your son first time wise, and a good man won't try and compete with his time. Don't try to force it or find someone, enjoy your child's toddler years as long as you can. As for letting people know you have a son, that is part of who you are. No need to hide it or feel weird about revealing it.
This may seem odd, but my husband and I, on our very first date, we told each other some of our background and also our 5 year plans, just a nice and casual conversation, we talked about our views on religion, family values, being financially smart, our parent's relationships... everything that shaped who we were, and we were only 22 at the time. Too many people date and never even bring that kind of stuff up until they are worried about marriage, or even after they are married. You don't need to be pushy or all emotional, but just a casual conversation about where you see your career, where you see your family and life heading in the next 5 years or so is a good thing to share. I would be wary of a guy who didn't have any goals or aspirations, or a plan on how to get there.