Scared for twins

Hello Ladies! I just discovered a couple weeks ago I am pregnant with twins. With no twins in mine or his families we were very shocked. Doing some research I see one of the biggest concerns with twins is premature birth. I have a "hearted shaped" uterus which doctors are assuming was the cause of my 10 month old's premature birth (water broke at 34 weeks, baby was born at 35 weeks) now I am terrified because of this shape I wont be able to carry the twins long enough. I see my doctor next week and not telling anyone because of how early I am. Just feeling a little alone and very scared. Any words of advice?