Congratulations on your pregnancy!
I'm sorry, I don't know what my hormone levels were. I have read that there is a lot of variation in general in women's hormone levels during pregnancy, as well as significant overlap between the 'normal' ranges for both singleton and twin pregnancies. So, all in all, I would be hesitant to use hormone levels as a sole indication of a multiple pregnancy.
You could always get 1 U/S and then UC if all signs point to go!
At the risk of typing stuff you already know: However, if you suspect twins, it is wise to get an U/S. Why? If the twins share a placenta (which is usually best diagnosed by U/S in the early weeks before many indications of twins develop - say 8-12 - by a VERY COMPETENT practitioner), they are at risk for developing Twin to Twin Transfusion Syndrome. It would be easiest to rule this out, otherwise you may end up doing more frequent U/S later in the pregnancy to check their growth and development to make sure one baby isn't thriving at the expense of the other - this is where we are, and I don't like it... ugh. Secondly, if the twins share an amniotic sac, you are in a whole different ballgame - very dangerous and requires hospital admission around 26 weeks, I believe.
Also, though I am at times disgusted that we had early ultrasounds, I think it really did make a difference for me to KNOW that I am carrying twins, because the demands on your body are pretty high; I was able to adjust my diet (tons of protein) and activity level knowing that my body was growing for two babies, not one. And I've made it to 39+ weeks so far.
I would not consider UC with twins until you figure out their configuration in the womb and understand associated risks. There are some UC twin mamas here who can prob help you a bit more.
Best to you, twins or otherwise!!