Hi mir4ea, first a bit of explanation on why you get that kind of shape in the first place - imagine instead if you had a sharp cornered profile and you wanted it to collapse down to a point in the same way, that would look like this:
So notice there that the corner takes a sort of diagonal trajectory as it collapses down into a single point - basically features of your profile curves follow that same kind of trajectory as they approach that point, it can then be pretty natural for some evidence of that path to be present in the resulting shape.
It seems that the main thing that you're trying to build has some broadly shaped areas like this:
Then in between those broad areas you want some more tightly curved transition areas in these areas:
So usually in NURBS modeling tightly curved transitions between areas are done with fillets - currently you're basically trying to directly model both the broad shapes and the transition shapes all at the same time, and that can work ok in some spots but it's difficult to make it work very well in spots that collapse down to a point because of the shaping issue that I described above. So for that end it could be better to put a fillet on that one area rather than trying to construct it directly. That would go something like initially draw a flat ended shape, and then if you don't want a totally flat end, model a curved end cap using revolve or sweep (here I've used sweep), then cut off the end of your shape with the curved end cap and now you have the end curved form and then apply a fillet on the edge shown to make the transition:
