Congratulations on your pregnancy! Just remember that many women don't even know they're pregnant at 5 weeks. The reason: the symptoms that make it obvious that things aren't normal haven't really kicked in yet. Maybe they've felt tired (but who isn't tired most of the time, especially if they have other children!). And not all women feel tenderness or morning sickness to the same degree, if at all.
I've had four children and two miscarriages, and I can tell you, every single pregnancy was different. I've only had tender breasts with my first child and with my last pregnancy (which I ended up miscarrying). I've been exhausted with all of them, but it doesn't always show up immediately. Sometimes it happens before I know I'm pregnant, other times it waits until week 8, and then I can't seem to keep my eyes open, no matter how much sleep I've had. With most of my pregnancies, the morning sickness seems to start as soon as I take the home test, but with the last pregnancy, I took the test because I almost puked while eating lunch and knew for a fact I didn't have an illness. I've heard that the stronger the symptoms, the better the chances of not miscarrying, but this past pregnancy had the most noticeable early symptoms of any I've had since my first, and I miscarried a week after taking the test.
I understand completely how hard it is not to panic, especially when you or people you know have experienced a miscarriage or other problems, but the best thing you can do is relax and take good care of yourself (especially when/if the symptoms DO hit).