If it were me, i wouldn't tell her until i was 18, then i would say that a nice boy that you've known for years has asked you out for dinner. That you would like him to meet her when he picks you up. Make it a special event, (the date) a really nice restaurant and movie. Maybe ask for her help to find something special to wear. Make sure he brings flowers for your mom. Give her the dream that she envisions for you. Once you are married, and the marriage is working, and you're on your way in your career, thinking or having a family (her grandchild) you might tell her in a special way. Tell her you know that she was anxious for you, so you didn't tell her right away. You planned the "first date" that she knew about in a way that would ease her mind. You didn't want her to stress out, being a single parent was stressful enough and you didn't feel that you were in any way at risk, and it was more important for you to protect her from anxiety than to tell her what you were doing. If i was a single mom i think i could understand being told that. The reason why you spared her the truth was for her benefit, and not that you wanted to get away with anything. The fact is if you are entering college at 17 you are a mature women already and able to make your choices, based on sound reasoning and logic.
Good luck. Take your time. Sometimes it's better to spare our parents from TMI (too much information).
Well, I certainly agree that if you tell your mom that you have been dating despite her telling you that you aren't allowed to, it is not going to make her think you're trustworthy on the subject. Avoiding "the same mistakes she made" doesn't start with a year of lying to your mom about guys. (For all you know, that might be how she began, too.) It's a shame that she doesn't think you're old enough to date at 17, but doing it behind her back is the wrong way to start. But I agree that you shouldn't tell her unless you want your whole life to crash down on you and to suddenly find her trust in you totally destroyed. I would even stop dating for a while so she won't accidentally find out -- if she does, probably a nun would find she has more sexual freedom than you do.
Just in case you're thinking you can't take a break from dating, I might point out that a best friend who is goal-oriented and treats you with respect about whom you use the phrase "I really love him" is not the same as someone about whom you can say heartfelt "I love him and can't imagine life without him." Also, if he is as goal-oriented as you say and such a straight-up guy, he should know full well he shouldn't be seeing you without your mom knowing. It should be a red flag for him that you are sneaking around.
You're 17 now, and soon enough will be 18, and that's when she doesn't have as many legal rights over your life. She might not pay to support you, though, if she dislikes your life choices, so tread very lightly even then with her about this topic. Or, at that point move out and do what you would like.
I think you should just confront her and ask her if you can date, say can i start dating someone. If she says no then say, all my friends are aloud to date. And if that doesnt budge her then bring up how you think that she thinks that you will make the same mistake. Tell her you are waiting for marriage. I feel like that would do the trick. Then if she does say yes then say that some guy asked you out and see if she says yes to this guy (your boyfriend). Dont tell her that you have been dating, I mean thats your choice but I wouldnt she would probably get really mad.