You don't need to wait in line twice just so you and DH can both ride - you show up to the line once and ask to do a baby swap. They will give the parent staying with the baby a card that will allow them to bypass the line when they come back for their turn. The exact logistics may vary slightly from ride to ride, but some form of baby swap is available at any ride with a height restriction. (It will not work if there's no height restriction, though, like if your daughter does not want to do Haunted Mansion.)

OP here. Thanks everyone but fall is really not into consideration for the reasons I have already given before. Plus, I like Disney as well and want to have a good time, not to be dealing with a 4m old and breastfeeding, etc. Also, do they even allow you to take babies in rides? I like going in rides with my husband and daughter together.

And on top of all I have said, I am planing on traveling to another country during that time of the year (much cheaper tickets).

I really want this trip to be about having fun with my dd while it is only the 3 of us

I am very sad about the fast pass issue though, because since our child is so young and can't ride anything by herself yet, it means we will waste our daily quota mostly on things for her benefit (Nemo, Peter Pan, Pooh, Tea Cup, Characters Greeting, etc) and will have to suffer (double the time since we have to go each one alone while the other parent stay with child) through the lines for things like Soaring. Ugh!

To the pp who asked me about talking to my doctor about such a long drive - I didn't ask anything because I will have more leg room than in a plane plus we can stop whenever we feel like and stretch our legs. My last pregnancy I traveled around the same time by plane to Disney as well, and right around Halloween. It was very cold.