Hi Melissa!
Disney does offer some infant-friendly rides, where the child can sit on your lap as the ride commences. These rides are normally slow-moving, plus usually offer a bar that's placed right in front of you and child. Here are a few rides I got on with my 18-month old son, who still preferred to sit on my lap as often as possible:
*It's a small world (Magic Kingdom)
*Living With the Land (Epcot)
*Peter Pan's Flight (Magic Kingdom)
*The Seas with Nemo and Friends (Epcot)
There are a number of additional pre-school friendly rides, such as Dumbo the Flying Elephant, but I'm not sure if an infant can sit on your lap for these rides, which spins around. I got on this ride with my 18-month old, but at this age, he could sit up in the seat next to me.
Hope you and your family have a magical vacation!