Dealing with loss

No, this isn't a post with advice on dealing with loss, rather, it's a "I don't quite know how to deal with this" post.
It's been almost 5 years since Henry left us and I'm doing just fine most days. It's the "special" days that are still a problem. We deal with Christmas by going away, that works. Thanksgiving gets pretty much ignored. But what about birthdays and the anniversary of his death?
I have a good friend who sends special gifts for the special days to make sweet memories and I am incredibly touched by her thoughtfulness.
Three years ago - or was it 4 years ago? - I came up with the idea of asking friends to have pizza in Henry's memory. It was his favorite food and we visit his favorite pizza place on occasion. Last year, K was visiting, so we invited friends and relatives to join us and there were 7 of us. It was quite nice. A nice distraction. Yesterday, there were 4 of us and it was fine. But, and I don't know if it's the still lingering cold or what, I don't feel so good today.
Yes, there are good memories to hold onto but there are still all those questions: why, what led up to it, why didn't I see it coming?
And then I ask myself: Am I dealing with this the right way? Shouldn't it maybe be time to just let go? I know I've moved on. But is it maybe time to put this behind me? I just don't know.
I've heard from a friend about another mother who lost her only child in an accident. She shuts herself in her house and spends her daughter's birthday remembering. No phone, no visitors, just herself and her memories. I can't do that and I don't want to do that. I know that isn't right for me.
Another friend organized a card tournament as a fund raiser in her brother's memory. The money raised goes towards a scholarship.
Still others have masses said on their child's special days. We did that for a while, until we didn't need them any longer.
I know this feeling will pass, but there's still the anniversary of Henry's death coming up and we will be visiting the bridge again - with flowers. Since it'll be the fifth anniversary, I am wondering if I should do anything else. But, if so, what? And, really, shouldn't I maybe just move on and treat all these days as if they were nothing out of the ordinary?
I just don't know.