If your bowl is still pliable it's not going to hold up. It's sad to say but it's time to junk it and move on. There's nothing wrong with the recipe mix that you used but we don't know if you didn't mix all the dry ingredients or made the walls too thin or if you added too much water. Just try again. I'd add sand to your recipe in your zone. I prefer for planters equal parts of cement, sand and sifted peat moss. You can substitute vermiculite or perlite for the peat if you like a "whiter" look.
I'm curious as to why everyone seems to be leaving things to cure for so long. Your pieces are 90% cured in 7 days. Most items that people are making can be unmolded in 24 hours. Very gently, clean it up by wire brushing or carving or whatever you want to do then spray with water, wrap back up in plastic for 1 or 2 days then place in a water bath to leach out the lime for 2 or 3 days. Good Luck! Billie

Vermiculite can be more difficult to wet than perlite or sand, so you might have added to much water. It does tend to stay soft a bit longer (so it's good for carving) but that's in terms of a day or two, not weeks.

Your dry mix sounded like good proportions. Admix or superplasticizer in your water portion might help.