M.W.
Hey Alison,
You must be feeling very overwhelmed and frustrated! I am a behavior specialist who works with Children with Autism (I am also 8 months pregnant with my first child). Before I started my career with this population I was a preschool teacher, so I would like to think I am able to give you some advice here. First of all, if your daughter does have Autism you can not blame yourself in anyway - this is the way she was made and although the road ahead will be difficult, she is still your child and needs your love and support.
What you have described does sound pretty normal to me - Kids all develop at different times and in different ways - you can't compare one to the next. The verbalizations you described could very well be her way of trying out new sounds or testing her vocal cords - toddlers are (as I"m sure you know) extremely curious creatures and sometimes their ways of exploring seem weird to adults. The bathing and play concerns are pretty typical, both tend to be cyclical (one month they hate the bath, then next they love it).
There are some questions you can ask yourself - Does your daughter make eye contact? Does she interact with you or your husband? Does she respond when you speak to her, or when you play with her? These are things your doctor will be looking for. Also, things like does she do any stimulatory behaviors (hand flapping, head shaking, rocking); does she have aversions to loud noises, certain fabrics, overhead lighting; has she "lost" skills she once had (language, motor skills, socialization skills).
I hope I was of some help; although it sounds to me like your daughter is ok - maybe going through an annoying stage, but overall "normal". Please let me know if I can be of anymore help... and keep me updated!!