My experience was the mitral position. First a repair that solved a valve leakage problem but made the valve too small, then 6 mos later a mechanical valve was installed. I've always been a distance runner so, like you, from the time I had the valve work done I have always clearly noticed the change. Here are a couple thoughts in case they're helpful:
I'm a hydraulics guy by education/profession so I've done plenty of research and had plenty of conversations about the valve size. The thread Pellicle attached a few days ago captures the key points. Summarily, during the operation the valve opening is sized/measured and the correspondingly sized valve is picked for installation. Essentially this practice matches the cuff to the opening. Of course this is critically important so that the new valve is solidly installed and there is no leakage around it.
Aside from a good installation; however, what we (the patient) need is flow. Better still is flow without much pressure drop. The heart muscle is going to work to obtain the flow regardless and the harder it works . . .. . well, higher blood pressures, thicker walls, faster rates, etc. So generally speaking, more area is better.
My surgeon referred to the sizing as: "true sizing" is when the selected replacement valve correctly fits the opening as sized/measured. "+1" is a size bigger. "-1" is a size smaller. Knowing of the problems I had with the repair he was able to go +1 for me. Sure, a larger valve is always possible . . . . but at the increasingly larger risk of causing damage to the native structure(s) the valve lies within.
Effective Orifice Area is the generally accepted parameter in hydraulics to simplify the myriad of variables that cause the pressure/flow relationship through a "hole" to be other than theoretically predicted for the perfect orifice. In my personal case, with my initial repair, the major factor was that my leaflets were stiff enough (calcification?), that after being tightened up to stop the leakage, they simply did not move out of the way nearly enough in the open position. With my mechanical valve, there is the reality noted that the actual opening for flow is smaller than the cuff size but also the apparatus (leaflets, rotation structure, etc.) sit right in the middle of the opening! If you are comparing valve sizes, I do agree that EOA is the parameter to compare but it's best to understand that it is a calculation and hence not quite as clear cut as measuring the outside diameter of something. Of course, the surgeons are also dealing with our living, flexible, biologic heart that (I imagine) isn't quite as easily/accurately/consistently measured as, say, the inside of a pipe!
When the time comes for another replacement, definitely have the conversation with the doctors about sizing and make sure they know that you believe what you have is currently undersized. There are definitely things that can be done; but understand that just as definitely there are limits on those things.