First and foremost, you probably don't have anything wrong with you. They're perfectly normal thoughts, though not ones people typically dwell on so intently.

With that being said, I've had the same experience when I was close to your age. I'm 22 now and I can say I'm completely over having such thoughts which, yes, they feel real but are actually rather irrational and silly. This (I think) is simply a product of you reaching an age where you're becoming self aware of yourself and how you fit into society in general, which is entirely a good thing. It shows that you're maturing and growing as a person. The clinging to your mother could be a sign that you're not wanting to jump into that role just yet (or at least that's probably some babble a psychologist would say).

I never enjoyed going out in public, alone or with anyone, and when someone came into the house as a guest, plumber, or in general stranger to me, I avoided them completely to the point of neglecting other obligations like eating. So you're not alone on this. The worst thing you can do is worry about it, and the best thing you can do is just make do. You can't control your siblings behavior, no matter how hard you try. And when someone comes to fix the pipes or dishwasher or what have you, just take it one step at a time. Address those feelings directly, accept that you have them, and deal with it as a rational person would. Don't let it be a damper on your life, because while you may not be able to control what makes you feel that way, you can control how you react and, to a degree, how you feel about it.