I think you did better in the first fight, which is funny because the height difference should have made it a little more difficult. The first two rounds were fairly good, obviously you flagged and slowed down in the 3rd. IMHO I think you could improve by being a little more methodical on closing the range, less rushing. While you still want to keep the agression and pressure style that you have naturally, it might help to keep on the 'brim of fire' distance and try to draw the opponents punches by convincing feints and work on slipping and countering his leads. This would probably work better against taller fighters. Against the second guy who was about the same height and reach as you, you may have done better if you had tried to outbox him a little more and used the jab, as others have commented. Your jab needs to be fast otherwise it won't worry anyone and they won't react to your feints.
I wouldn't be too worried about comparing the fights in terms of progress because the opponents had very different styles and problems which you had to solve.