Twins?

Does anyone here think they might be pregnant with twins? I'm five weeks one day, but I started experiencing symptoms a week before my missed period. This is my fourth pregnancy and with the others I didn't have symptoms until later on, but this time I have had everything nausea, fatigue, terrible acne, HORRIFIC heartburn-the heartburn has been so much worse. So I wonder if I might be expecting twins and I don't know how to feel about it. My mom had identical twins (twins don't run in the family) and she would rather block out the pregnancy and first two years of their lives-- she had a really rough time of it. All babies are blessings, but twins when I already have three children (6, 4, &17mos) seems really daunting.