My son was about 7 months,when he was able to sit up good without support and when he was able to crawl.No need for non-slip with my son, just a regular bathtub. I was worried,but for no reason because he did great without the baby bathtub.He is now ten months and still doing great in the "big boy"bath.
I had the same question when my baby was born, he pooped literally every diaper change!!!! I even called the doctor and they said it was normal. As long as she is having bowel movements and staying hydrated she is fine.
i use the Evenflo Triumph Advance DLX the ladies are talking about, its safe,nice and big and it is so comfy, .. well I can't fit in it but you know it looks very comfy,LOL and Jayden loves it... just do some research and see which on is best for Jayden