Increasing gain before feedback

My band has feedback issues- we usually just barely get enough volume to go on, but we are always dangerously on the edge of feedback. We could use advice on increasing gain before feedback. Here's our setup:

We use in ear monitors, so there are no stage monitors.
A&H Gl2200
Crown xti4000 (ch. 1 feeds both subs, ch. 2 feeds both mains)
Peavey PV115 for the mains
Peavey PV118 for the subs
Dbx1046 compressor for vox, backup vox, guitar, kick
Samson scom4 compressor for drum mix, gtr. 2, bass
Dbx 231 eq
Lexicon mx 200 reverb
5 vocal mics (sm58)
2 guitar mics (sm57)
Samson 7-kit drum mics (kick, snare, 3 toms, 2 overheads.)

We usually try to use the graphic eq to eliminate 2 or 3 trouble frequencies. If there is still feedback, we bypass all of the compressors. Often there is still feedback after all of this- so we set the volume just before the point of feedback and get through the show.

We play fairly small venues. Too many open mics? Bad speaker placement? Would mic or speaker upgrades help at all? How can we improve our gain before feedback?

Thank you for any help. BTW - gearslutz has taught me so much- I'm a long time reader, but this is my first post.