I'm not sure how to say this politely, but I think that you are mistaken. Perhaps you are not including some relatively high monthly fees? Perhaps you are not accepting all major cards? Maybe you are including a large percentage of debit cards? Maybe all your transactions qualify for some particular promotional rate?

I do about that volume, mostly card present, and think I have decent rates. I think I'm at Interchange plus .2% plus 1 cent per transaction plus $20 per month, and end up around 2.7% for total fees. I'm sure one can do better, but not by a lot. I'm willing to bet a considerable sum that you are not actually paying 1.6 percent once it's all added up. But if somehow you are, the loss of the bet would pay back quickly if I could get those rates myself!