T.S.
Most providers will take children as young as 6 months. We go to an in home provider, but some people choose care centers. Our provider is really good and we don't have to worry about a large age gap between the kids, because she works with infants and toddlers primarily. She's licenced and can only have 2 children under the age of 1 and I think she's limited to 4 above the age of 1 (but since she's todder and infant, the age above 1 is cut off, but I don't know exactly where.) If you're afraid of placing your child somewhere with older children, looking for a infant/toddler provider might be worth a try.
Your daughter will get sick a lot too, our son gets lots of colds...but I don't necessarily think it's a bad thing. I think of it as his immune system getting stronger, so when he's in school, maybe he'll miss more.
But I can tell you as a full time working mom, if you have the opportunity to stay home with your child, I'd take it. Understanding, sometimes it's nice to get out of the house, but I hear there are several mom's groups for stay at home moms you can join and they have several get togethers.