Hi krispy, I don't know if it is normal. Although I read the same info as you did.. signs of an early miscarriage. However you are not bleeding or spotting, so you may not be miscarrying at all. It's better to go to a doctor for a scan.
If you previously did a tummy scan, this time, you should be able to see a sac still. If you previously did a transvaginal scan, you shoudl still be able to see a sac transvaginal. Don't freak out if you previously only saw a sac transvaginal and can't see one now with a tummy scan cos tummy scan is not as sensitive as a transvaginal scan. Also, scans are operator dependent. If it is an inexperienced doctor, she/he may not see the sac even if it is there (esp for transvaginal).
If you are at least 6 weeks, doctor may already be able to detect heart beat.
If you knew your previous HCG level (from prevoius blood test), you may want to ask doctor to take your blood again to check present HCG level. If it is a miscarriage, HCG level will drop. If you did't previously test HCG level, then you may be asked to return the next day or in a couple of days to recheck HCG level. HCG level is differnet for every woman at the same stage of pregnancy. It is the "relative" HCG level for the same woman during the same pregnancy that can tell doctor if you are miscarrying.
In the meantime , don't worry too much k.