You are right that every pregnancy is different, so don't worry yourself needlessly. Your dr appt is next week.. so don't start worrying unless the dr says you have a reason to.
But keep this in mind:
Do you know the date of conception? When you took the test at the beginning of Dec, you probably WEREN'T pregnant. If the first day of your last period was Nov 24, then you probably ovulated sometime around Dec 4-7 or so (about 10-12 days into your cycle). If your irregular period is often "late" then you may have ovulated even later than that. Either way, you probably are no more than about 5 weeks along.
So don't fret, you may STILL get horrendously ill!! :)
For what it's worth.. I always heard that girls made mom's sicker b/c of the hormones... so maybe this is a boy. lol
There are SO many "tales" about what this means or that means... it could be as simple as your body is receiving more appropriate nutrition this time... not lacking B vitamins or magnesium that you were short on the first go around or something like that. But nobody really knows.. if they did, there wouldn't be women out there suffering with morning sickness! So you cannot rely on being sick or not as meaning ANYthing.
Try to enjoy the fact that you are not miserable (or at least not yet) and count it as a blessing!
Congrats on the pregnancy!