Burrageara Nelly Isler

[cavycat]

Hi, I bought this in November in bloom. It did well, finished blooming about 2 months later, set up 3 new spikes. But ever since I've had it the p-bulbs have been getting more wrinkly (they were plump when I got it) and the blooms on the new spikes are much smaller than before. Also they've started to die after only a month.
There is new growth (roots and new p-bulbs) but I don't understand why the flowers are so poorly.

The plant is on a windowsill in a westernly window, getting intermediate temperatures, potted in s/h.

Anyone got any clue what I'm doing wrong?

Thanks