It's really difficult to confirm twins with the doppler at this point in your pregnancy. If you're really concerned now, you will need to get an u/s. Measuring "big" prior to 20 weeks doesn't really mean anything as fundal height is highly variable in the first half of pregnancy. Looking bigger is certainly normal with subsequent pregnancies. I had a brief moment of thinking I was having twins, too, b/c I was popping out at 7 weeks when I hadn't even shown at all until almost 7 months with my first and 4ish months with my second! Unless twins run in your family or you used ART, they are not very likely. I have no doubt you're sicker and more tired since this is your FIFTH baby! My goodness mama, you're chasing around 4 other little ones!
But you could wait and eventually your care provider will be able to palpitate both of them. Or you could opt for the 20 weeks u/s and do the anatomy scan to confirm. Good luck with your decision! :)
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