Here's a good question you need to think about. How long do you expect to continue living with your mom? If you expect to move out at some point in your life, look at it from her point of view. You leave, she's alone. Everyone needs a companion. Just like you have your friends, and will probably date people, your mom needs that too. You claim it's YOUR time with her, well what about HER time? You said you have told her your feelings about him, have you ever met the guy spent time with him? Or did you just make a judgment based on a one sided story? Maybe what you need to do is go meet the guy, spend some time with him, see what he's like. You never know you might like him. He might be perfect for you and your mom. Maybe he's not. You'll never know, but keep an open mind. And if your mom really likes him, she'll also want to see how he interacts with you, just be polite and see what happens.
As for seeing a counselor, maybe you should. It's a good way to just get your feelings out on the table with out anyone judging you. It's confidential, if you say so they will not say anything to your mom. But it might help give you a safe place.
Seeing how your mom probably has been out of the dating world for a bit, she's probably a bit rusty with the who time concept. If she continues to date she'll get better at it. Just keep in mind the world wont come to an end if she's late. If she's REALLY late in picking you up, give her another call, just as a reminder and to make sure she's okay. Now is the perfect time to show responsibility, show your mom your growing up, you never know what will happen.
And as always before you go making judgments try to see the whole picture, it might be way bigger then you think.