Far be it from my right to judge and give advise to such experience player...
However, if you've seen my post in strategy and tips (desert start), I have learned a few valueble things from that game (yes, it was lost eventually, but only by diplomacy and i was able to survive!!!):
This could help, hope it does: I've waged war on Germany, which was much stronger than me and had better units, but using cannons, I took three cities. The war weariness was killing me (democracy), but they came asking for peace, so I guess they had the same problem (republic). I made peace and I think that was my biggest mistake. I had them broken and should have switched governments to keep on taking their cities. If you have similar situation, consider that, since the benefit will be more land, significantly weaker AI versus the few turns anarchy and more warlike government...
Other than that, I think your position is not that bad, at least you are not sandwitched in between the two AI...