At 195cm, it's time to take advantage of your height. 17-20 SPL at a single tempo of 1.1 is a pretty big range.
Something isn't quite adding up though, unless your turn is really slow or you're pausing a couple of seconds on 25's, 17 spl @ 1.1 tempo is a 1:34 100m pace - and 20 spl @ 1.1 tempo is 1:49 100m pace. I suspect you are closer to 22 spl @ 1.1 tempo is 2:00 100m pace. This all assumes your flight off the wall is 5m and you're not pausing on 25's.
Given your height at 195 your ideal "green zone" would be 15-17 spl. I suggest first finding a slower tempo between 1.1 and 1.3 where you can easily swim 15-17 strokes consistently. i.e. 16 spl at 1.3 tempo is roughly 1:44 100m pace. 1:44 pace is in the upper 10% of triathletes. A sustainable 1:44 pace in 2.4 mile swim (no currents) 64.4 mins or 1:04:24
This brings me back to the "slow" question. If you are using your Garmin and swimming into a head current, clearly that's not a good measure of true swimming pace. Find your sustainable pace in the pool first *without your Garmin*. Use the Garmin for reference only in open water after your swim.
If you are at 21-22 spl at your height, something is causing those hips to drop shortening stroke length. 1. Main issue is most likely head position, especially when rotating to air - head lifts for air, spine bends, hips drop. Like stomping on the breaks each time you breathe. 2. Reaching high and flat on surface with recovery arm/hand. 3. Busy kick and/or leg splay for stability, this can drive hips down too. I often see a combination of 1, 2 and 3 above when swimmers roll to get air. Fix these issues and you will discover you are capable of a 1:44 100m. This pace means balance and core stability, not power.