Since you say your gas consumption is very good when diving quietly, I will assume that you have already got a pretty nice, rhythmic breathing pattern.
That said, the amount you have to breathe is set by the CO2 you generate. CO2 production is increased by any increase in metabolism, so muscle activity will mandate moving more volume through the lungs. Swimming into resistance (current or flow) requires the diver to work harder than just floating or swimming slowly, so it will ALWAYS increase gas consumption -- if it doesn't, you are at risk for CO2 retention, with the consequence headaches, nausea, and worse.
So, how can one minimize the amount of increased muscle activity when swimming against current? Bob nailed a big one, which is trim. The smaller the cross-section you present to the water, the less resistance against which you must swim. Proper trim is a combination of body posture and static weighting, and with a single tank, it is almost always possible to adjust the two to gain horizontal trim.
HERE is a good article on achieving good trim.
In addition, using a propulsion technique appropriate for the situation is important. Several people above have recommended the frog kick; although it is the primary kick I use, it is NOT ideal for battling current, because it incorporates a glide phase, which is a period where you are not driving forward and are therefore losing momentum (or even moving backwards!). Much better in current is a kick technique that provides continuous forward force, which is some sort of flutter kick. Flutter, done with a long leg and from the hip, is a difficult kick to do with much force, because it is generated by short muscles with little mechanical advantage across the joints you are moving. Modified flutter, done with a. flat body and bent knees, is much better, using long muscles with good mechanical advantage, and furthermore, muscles most of us use a lot, which are therefore fairly strong to begin with.
HERE is a good vide of the modified flutter kick -- note the long, flat body, and minimal movement of the knees.
Finally, it may be necessary to look at the equipment you are using. Soft fins, although they minimize the muscle effort needed to move them, also do not transmit much of the force from your muscles to the water. Therefore, they tend to require a rapid kick cycle, which ends up being a lot of work in total. (Much like pedaling a bicycle in very low gear.) Very stiff fins efficiently transfer force, but require significant strength to use. Finding a fin that works for you can be quite individual, but in general, you probably want something that has some stiffness (paddle rather than split) but isn't tech diver stiff.
And remember, too, that you DID manage bigger tanks, even if they were more work, so that is always an option.