Could I Be Pregnant With Twins?

I am currently 6 weeks pregnant with my second child. I don't have an OB appointment for another 2 weeks so I was wondering if someone on here could help me out until then. I'm thinking I could possibly be pregnant with twins due to some unusual and/or more severe symptoms that I didn't have with my first baby. First of all, I am hungry literally ALL THE TIME. And I don't mean the usual "eating for two" or "I'm craving this or that" hungry, I mean I'm actually hungry to the point that my stomach growls like crazy; even though I have been eating adequately. Second, I've already gained six pounds and I feel like I am huge. I can already see and feel an unmistakeable "baby bump". Also, I have been very uncomfortable when trying to sleep. I can't find a comfortable position; it hurts if I lay on my stomach and I feel like my belly is already getting in the way of being comfortable. Lastly, my breasts have already swelled to a full cup size bigger and my nausea has been twice as bad as it was with my first pregnancy. If anyone has any advice or can assess these symptoms for me, I would greatly appreciate it. :-)