Looking at the curves I can’t quite work out what it is you need to develop.
(ignore that it’s the PC version you can follow the same steps)
Here’s a quick (long winded!) video of how I’d get to a basic shape using what you’ve presented. From there you should be able to cut stuff away or build upon it.
Sometimes it’s too much to ask of the program to do everything in one hit - you get more control if you do it in steps - it also gives you insight into how you could approach the problem in the future.
I hope that helps. Apologies if it’s nowhere near what you’re looking for
Forum_frame_02.3dm (117.7 KB)