YAabsolutelyNBU.
Like you, OP, I have 2 DC - a DD who is 19, and a DS who is 11. But, if all had gone as I'd hoped it would, I would have 4 DC. A second 11 year old, who should have been DS' twin, and a 15 year old.
DS' twin was lost at 8 weeks and... I don't know if I'd even "know" at that stage of gestation, but I'm convinced that it was a girl. Even before I started to lose her - and at that point, I didn't know for certain that I was carrying twins, because I'd not had any scans - both I and my mother were adamant that there were two little lives inside of me. Consequently, I named her: Carey Grace Anaïs (which will probably "out" me if any of my close friends are reading this thread!). I remember/celebrate her brief "life" every April 10th.
The 15 year old I lost at just after 3 months and was a boy. Although I remember him every April 23rd, and named him George Andrew, unlike DS' twin... my family and ex-P's family don't know about him. We were in a period of NC with my parents and ex-P... well, he's very good at not communicating about anything that he thinks his parents are going to disapprove of. They don't know about DS' twin, either... and, actually, they didn't know I was even pregnant with him until I was 27 weeks, because a grown man of 29 was too afraid of their reaction (bear in mind that he and I had been together since we were 14 at this point...).
Unlike PP, I don't remember them on their due dates. I choose to do so on the dates when I lost them. When their lives ended. When I, as their mother, was bereaved of them. Both DD and DS know about them now. MC are horribly common on my maternal line, and so I wanted DD to know that if ever she should find herself losing a pregnancy that it's not something to be ashamed of, or that ought to be hidden. That she can always communicate about it with me, if no one else. My DM lost seven pregnancies between my older brother and myself, and deals with it by not talking - which is fine, for her, but when I went through the same experience with DS' twin, and was terrified enough to want my DM (because there was a very real chance I was going to lose DS, too, at the time), she couldn't have been less understanding/sympathetic if she'd tried.
MC isn't something that we, as mothers, ought to feel ashamed of, or shamed about. It is a very real risk with every single pregnancy. Women need to communicate about it and support one another when it happens, or has happened. And yes, as the mothers of these putative babies, we do need to be able to grieve for their losses, to remember them as we see fit. Because in, and of itself, that is part of the healing process (not that I think we ever will heal from the loss, but we're more likely to do so if we're able to talk, and cry, and perhaps even get angry about the fact that they didn't survive).
But it's not our fault that we lost them.
It really isn't.