Jealous toddler?

I am 33 weeks along and have a toddler who will be two in feb. I've never had any problems with her besides the normal "terrible twos" with her seeing how far she can push things. HOWEVER here lately she's been throwing fits a lot more and at the same time always wants to cuddle as close as she can with me. I just don't know what to do to make sure she knows that even thought she's going to have a little brother soon she won't be left out or anything..just would like experienced mamas in this area to give me some advice please. 😢