I am far from an expert but I would say that you would be better focusing on the yellow stamen (I had to google this ) instead of the petals. Looks like the lighting is spot on to me though. Can we see a photo of your home made light box as I would be interested in getting results like these without all the outlay
Its just not working for me I'm afraid, I'm not a fan of the composition, I cant see where it is focused, its seems to have poor colour and noise. Sorry. I like cyclamens too, have another bash with light on the cyclamen rather than under it.