I will be 18 weeks tomorrow, my question is about my birthing plan.

Talk to your doctor about your options regarding a waterbirth. Not all hospitals allow them and often doctors only work at one hospital. If there is a hospital in your area that does offer water births and your doctor doesn't work at that hospital you'll need to find a new doctor.

I haven't had a water birth but I did get to spend a lot of time in a bath tub during my first labor/delivery. It really sped up my labor. I went from being 3.5cm dilated to 8.5cm dilated in an hour. The bath was very relaxing and I'm extremely excited that I'll be able to do the same thing this time. (The hospital I went to for my second didn't offer a tub.) I actually got a little bored in the bath so I'll be mixing it up a bit this time. I'll be having a natural birth this time since I had a horrible experience with my epidural last time. (I had a spinal block shot the first time.)

As relaxing as the bath was, I didn't find that it lessened the pain of the contractions. But, I wasn't prepared for a medication free birth and hadn't taken any childbirthing classes, so I didn't have any techniques for dealing with the pain. 

I would also advise against a homebirth. Even with a complication free pregnancy there are so many things that can go wrong during labor and delivery, it's best to be in a hospital where any necessary emergency procedures can be performed immediately. I read an article from a doctor on webmd about a recent study that found that healthy babies born at home were 20 times more likely to die than healthy babies born in a hospital. Also, my mom's boss, who is in her late 20's, recently had a home birth. She labored for 50 hours, pushing for a significant portion of that. Ultimately her midwife sent her to the hospital to have a c-section. A few days later she had to have emergency surgery to repair her bowel that had ruptured as a result of the endless hours of pushing. This may only be one story out of hundreds or even thousands of problem free home births, but is it really something you want to risk?