I believe that it is a far greater failing to be dependent on the somethings and presences in your life for your identity. People often cling to their activities because they do not know how to be content with themselves alone. When they are doing nothing, it is only because they have nothing to do, not by choice, and it leaves them feeling ungrounded and empty. Many plan their lives so that they never have to face a moment when there is nothing to do. This may make them interesting to other people, but it is not a sustainably healthy way to live. It does not allow for those moments you speak of in which there is nothing. Solitude, isolation, emptiness of surroundings and atmosphere give one a moment to recover, rejuvenate, de-stress, and be mentally prepared to meet the next passion or engagement. It is rare that anything/anyone is so purely good and comforting to a person that there is no attending thoughts of business, past stress, or future obligations. If you can find comfort in nothing, then you have simply discovered what works for you, which can only be a good thing. So much of life is simply learning how to care for yourself. Finding what works. There is no right way.
As for suicide, apathy, passiveness... I think we all struggle with these thoughts and feelings to a greater or lesser extent. Certainly, I know that apathy and passiveness were predominant factors in my life for the last 6 months or so. It made for a frustrating, hectic time. I am in a much better place now; and what I learned from that is that when I'm doing too much, engaged and committed to too many things, I lose my commitment to myself. Perhaps you do not find this true, but at least listen to the voices of the people around you. You are indeed perceived as and known for being an active, engaged, talented, go-getter, driven, fun, social person. That is not a lie that we see. You can't fake that.
So, when it comes right down to it, you have people and things that can comfort you, should you feel inclined to reach out for them. It is true that some people stubbornly cling to solitude and refuse to reach outside themselves for the help and support they need to stay healthy. They let themselves be hurt little by little and hurt themselves as well because they don't let the people in their lives close enough to help them. But as best as I can tell, and I would go so far as to say that most people would agree with me, you are far too engaged in and committed to your life for this to be a great concern. The nothingness, even when you are happy, is a balance. If you feel you are avoiding something, then face it; but don't be afraid of taking comfort in nothing.
I'll leave off here and leave room for some other comments now. I hope that this wasn't tedious or irksome to you. I just wanted to share my thoughts.