Why does artificial light make composite fillings on teeth visible?

I had a bad gum infection during my pregnancy and as a result my gums receeded and left me with a few quite unsightly holes in between the front teeth. My dentist advised me to get them filled up with composite fillings, which I did. They look fine in very natural to darker day light, but as soon as you enter a space with some neon light, like a supermarket or an elevator or even a public toilett, you can clearly see the patches on the teeth. That makes me feel very uncomfortable, because now I don't know when people can see the patches, and when they cannot. Sometimes I think I should have better stayed with the gaps as I find it almost worse to show off patched teeth when you smile.... is there any solution to this? I doubt it there is a way back now to get the caps off again... and veneers are most likely too expensive.... ;(....