Nerines

My Nerines have me confused. Most of my normal pink ones grow in the bed you can see in the middle distance here:

I have a lot of white nerines that look like THIS. They are delicate but prolific. Well, the other day I saw some that were twice as tall, and stronger, but quite sparse.

Today I was looking at my pink ones. Last year, the only ones that flowered were the ones near Mum's bird bath, where they were frequently watered. And they were ginormous (ie big and strong). Now, the main lot of pink nerines just near them are finishing flowering, and behaving like normal nerines - flowering from bare ground, with the leaves gone ages ago. And the ones that flowered last year were, up until now, just a lush clump of green leaves. And today, as the others finished, that lush clump of green leaves has started to throw up buds.

I just don't understand my nerines.