Welcome Sara-May! Glad to have you here on BellyBelly. Thanks so much for sharing your story, and I hope you have a great birth!
About waterbirth and birth tubs - I gave birth at home in my own bath. It was quite nice, but I can't compare it to an actual birth tub. I've never tried one of those. My bath is a large corner tub with whirlpool jets (which we used in labour, about until I started pushing - they were wonderful!) I sat semi-reclined against one of the sides of the tub, and never budged - you couldn't have moved me with a truck. It was exactly where I wanted to be.