> But since I don't wanna be potentially replaced by competition I haven't taken vacation in years (that was not problem before since I was not that busy and could rest enough every day to have free morning or afternoon) and I don't won't to refuse any projects to miss on money I can't imagine taking vacation, because I'm not gonna lose only vacation expenses, but also similar amount in lost income for every day I would not work.

I think that's the key: afraid.

Having too much work is actually a good thing! It means that you can afford to increase your prices. Then use that extra money and go on holiday.