Could I be having twins

I am 5 weeks pregnant going by my last period this pregnancy is so different to my last. 3 pregnancies I was terrible sick with my last 3 singletons thing is this time my boobs are huge and wreck they are mega sore my nipples are huge but I have no sickness but I'm eating like a horse about 3500 kal a day and drinking gallons of water and want nothing  but spicy food and anything lemon 1 I normally hate anything with spice 2 I don't really like lemon in fact I'm that bad my sister just took me tesco to get lemon cake ! By now I'm normally puking so bad that I'm in hospital with it!!!! my mum had twins her sister had twins and her daughter did could I be having twins ?????  I can't stop eating