K., I'm an OB nurse and from my experience, you start to feel morning sickness at any time. Also, all pregnancies are different so even if you haven't felt this way in the past it doesn't mean that it wouldn't happen this time. Over the counter pregnancy tests have gotten really reliable over the years (you can repeat the test in a couple of days), but the blood test in the office is going to be more accurate. If you are concerned, just call your OB and see if you can get in for a preg. test in the office. If it is positive, there are meds that they can give you for the "morning" sickness. Whether you are pregnant or not, if you can tolerate it, you should start taking a prenatal vitamin (if you aren't already). All women of childbearing age should take a prenatal vitamin daily because the folic acid supplement is so important to the development of the baby in the first few weeks....even the ones when you don't yet know if you are pregnant. If you take it either way then the folic acid is already on board.
If you get into the office and you find out that you are not pregnant, they still may be able to figure out what is causing the nausea and help treat it.
Good luck!