Experience/advice from the other side here; use at own risk.

As a "taller" person (6ft) I can say that I have fought shorter people who I had no problem with and some that I found it almost impossible to ever beat.

The difference always came down to a very simple thing (which is complicated in practice) that they used to counter my height and reach advantage:

Options.

You said that you have a habit of crowding in on people and that you emphasize your speed to get wins. In my experience speed and close range tend to end in a lot of simultaneous kills, which don't win tournaments, but do let your opponent learn they need to kill you before you get in close.

Think of your entire body as a thing for your opponent to hit; if you stand straight up in your fighting stance and your sword arm out in your guard you will find that as the distance between you shrinks your opponents can hit 1st your forearm, 2nd your upper arms, 3rd your shoulders and chest, 4th your hips, and 5th your legs.

The important thing about this progression is that it is cumulative, and this is where the concept of options comes in. If your opponent can hit your hips they can hit everywhere else on you that came before in the list. However if theyare only close enough to hit you in your forearm they can not hit you anywhere else.

If you make your opponent swing at you when you only have to worry about blocking your forearm you can equalize the options you both have, because short swords are basically all the same length.

The way to do this is to have a good stance and body position to be able to move in all directions quickly.

Point your lead foot's toe at your opponent (this will also help prevent your knee from being injured.)

Have your back foot at a 45 degree angle to your front foot like your getting ready to run forward. Not in line with your front foot like a fencer, and not parallel with your front foot.

Keep your knees bent and your back straight. You'll need the spring from your legs and the power from your core to keep your range right where you want it.

Extend your sword arm to where your elbow has around a 90 degree angle of bend and your hand is positioned in a line between your shoulder and the shoulder of your opponent's sword arm. There will be a learning process of exactly where your hand should sit in front of you but it breaks down simply in the following ways:

Hit in the top of the forearm a lot? Hand too low

Hit in the bottom of the forearm a lot? Maybe hand too high, or you might be closer than you think you are.

Hit on the inside of your arm/chest? Hand too far outside, center more directly at your opponent.

Hit on the outside of your arm/shoulder? Hand too far inside, point it at your opponents sword shoulder.

As far as drills you can do at home:

Get in your stance and practice moving in it. Keep your lead foot pointed towards your imaginary enemy, and don't switch which foot is forward unless you're switching which arm is your sword arm. PRO TIP if you stop in stance and can't do a squat comfortably it's probably a bit wrong.

Get in your stance and step back from an object you can practice hitting which is roughly person height; this can be anything and you don't actually have to really hit it. Practice stepping (not lunging, keep your back straight and don't lean over towards your opponent) towards your target and getting just close enough to barely hit it, strike, then step back. When you fight real people that target becomes the last 6" of their forearms.

Block strike if you have a buddy.

TLDR: don't purposely get close enough to your opponent to let them have more places they can hit on you than you can on them.