Also, you might look into buying yourself a compressor if you haven't already. I had exactly the same issue and I bought a cheap-ass behringer Minicomp along with the Preamp and EQ, and after some time of getting the setting right my voice is now much louder and I get *less* feedback. People saying that a compressor will ALWAYS create more feedback just don't know how to set it up correctly.
Personally, I've tried IEM and wedges, and since I have a compressor it makes absolutely no difference to me in terms of hearing what I sing. I always wear earplugs, even in band practice. I am very concerned about my ears.
In the long run I see myself going to in-ears because then I am independent of shitty equipment/sound people at small gigs. I don't care how bad they .... up the FOH sound as long as I'm hearing myself well. I need it to be confident, and that's half of what makes a good show.