Congratulations on your pregnancy! As it seems you've learned, sex while pregnant requires a little extra creativity, but there are a variety of sexual positions that may suit you and your husband as your pregnancy progresses. While I have never been pregnant, I do remember Jenny McCarthy saying that the only position she could successfully have sex in while pregnant was doggy style. Perhaps that's a good place to start.
Obviously, traditional missionary is out once your tummy starts to grow. However, there are still ways for him to be on top without your bump getting in the way. One of my favorite man-on-top positions is called camel. You lay on your side with him kneeling at your vagina - one of your legs goes straight in between his legs and the other wraps around his leg or waist (depending on how high you can comfortably place it). I think it’s fantastic. Another variation on this position is called the splitting bamboo.
You could also have your husband sit in an armless chair and have sex straddling him. You need to have strong thighs to keep a steady rhythm up and down, but it could be fun to try it briefly.
Here is a full list of sex positions, with definitions and pictures. I recommend the hero position, scissor position, or crouching tiger. The curled angel has both you and your partner on your sides, which can build intimacy and relaxation. Prefer to be on top? You could try the cowgirl or reverse cowgirl, the balancing act, the ape, the acrobat, or the cross. The success of these positions will depend upon yours and your husband’s flexibility and strength. Don't be afraid to make minor modifications, especially as your pregnancy progresses. Look at this as your chance to experiment and have fun. And if you stumble across something that feels good, stick with it.