Hire a professional wedding planner.
You decided not to "waste" money by hiring a professional wedding planner. After all, you have done most of the wedding planning already and your mom will be able to help out the day of. Maybe your reception venue also provides someone to assist.
This is what we see when the wedding day arrives: Mom is running around crazy because she is trying to get herself dressed, you in your dress (and can't figure out how to do those loops on the dress with her new manicure), checking to make sure that the groom has arrived, all while keeping with the time schedule. But wait, she isn't wearing her watch because it doesn't "go" with her dress and she doesn't have a pocket for her phone. Now you are running late. And that causes you stress. Thus the photographer is running late and having to quickly make up time on the photos, which might mean that you don't get all of the photos that you wanted. More stress.
Now onto the reception. The venue said that someone would be there to assist you. But for how long? Make sure you know what time they leave. What if they are just there for the introduction, 1st dance and cake cutting? What about the rest of the evening? Who is going to put snacks of leftover food in your get away car? What about your luggage? You and/or your mom will end up having to deal with issues that you shouldn't have to worry about the day of your wedding.
Hiring a professional wedding planner with a good reputation will be the best decision you make (other than hiring a great videographer, but we will get to that). I don't even know all of the little things that wedding planners take care of, but I do know that weddings run sooo much smoother when a professional wedding planner is there. We get better footage, the photographer gets better photos, your wedding party and guests will appreciate the organization. Let your mom be the mother of the bride, let her celebrate her daughter getting married. You, as the bride, do whatever you can so that you can enjoy the day. It really goes by so fast.