There's a lot of frustration in your post, frustration that you wouldnt normally see from a relaxed, well adjusted person.
The people that are close to you are trying to tell you that you have too many projects, do you think they are doing this to hurt your feelings or to put you down ? The answer is probably 'no', they are doing it out of concern for you. You should look at what they are saying without trying to defend yourself from them, try to analyze their points carefully without resorting to "...yeah but you dont know what I can do" or similar defensive arguments. They have a unique view of you that you cant see.
In the last three months, how many projects have you finished ? How many new ones have you taken on ? Do you ever hire anyone to do any work for you ? Why not ?
Promise yourself not to take on one more project before you complete two others. When you find yourself saying "I can squeze this small one in" or "this will only take me a day or two" to justify doing more, then you probably are doing too much. Also, if you think the whole idea of not taking on any more projects is a stupid idea, they could be right
Take two notepads, in the first one write down all of the projects you are currently working on or in the middle of, or havent yet finished. In the other write down all of the other projects you are planning, or need to do, but havent yet started. Next take this to somebody that is concerned for you and knows something about the projects, and have them write down what they think are realistic time estimates for one person to do/finish the job. Odd's are one of two things will happen, either you'll be amazed at how much time you have to devote to your projects, or you'll argue with how unreasonable their estimates are. Keep these notebooks up to date as you finish or start new projects.
I've got too many projects myself, and have only lately begun to realize it. Good luck.