married moms over 25+ , I need your input on pregnancy. I'm terrified of it

SO and I have been together for about 10 years. He wants a baby. I kind of do but I am terrified of pregnancy and the changes that comes with it. I feel like I will miss my liberty, spontaneous moments, etc 
How does one get over this fear? I've been feeling like this since I've been 12.  I am afraid I am not cut off for motherhood and I feel very strong about it. I feel sad that I think this way because I know he wants a family.