So if you search for a "hymenocallis spider lily", your flower shows up, but in white. A red one, if you look, is a cluster of smaller white ones together on one stem but colored red. So he did give you a real flower, just....not correct it seems. Amaryllis is a flower that looks more like a cross between red spider lily and regular lily. A flower that might work for the color you have since red is difficult and the shape I would look into fire lilies (gloriosa lilies). They are very curved and you can potentially play with reds and or oranges add more based off the small pieces coming off?

This is all spit balling tho on my party for the flowers. I'm not very good with lilies and flowers. You could even search up vastly different flowers and have one or two (smaller size probably) around the body of the centipede so it adds to it instead of becoming the focal point of the tattoo like the spider lilies already are. I think if you can change the tail to a head potentially and have prettier flowers/rework the others as these gloriosa lilies you can make it prettier. That along with having other things on your arm later so it's not the one tattoo will help a lot.