Hoping for #2 but.....

I'm 26 and ready to have #2 for me & #1 for my boyfriend, he's 30. My first is 8yrs old. She was born prematurely at only 28wks gestation. Worried though that my 2nd will be early to..? Ma and my boyfriend gained some weight over the past 2 years and because of this, we actually haven't had sex for almost a year now! We are self conscious about our bodies now, especially me =/ We want to try and have a baby though before my first gets too much older. Just got over AF today so wanna get started on TTC soon! Prayers are much appreciated!! And good luck to everyone else who is TTC! Thanks for listening!