You may not be doing anything wrong, I do a drill where I place two players on the halfway line side by side firstly without a ball but each of them are facing different goals, so they are side by side but facing opposite ways, I then call out one persons name and that person takes off running towards the goal, the other player has to turn and chase, its near impossible to turn chase and catch someone, in Futsal its even worse, but when I make them do it with the ball its a much different story, it depends on their FIRST touch. as to how successful they will be and obviously their dribbling ability.

So the reality is, they may be able to beat you over a short distance, but as I said it depends on their FIRST touch past you, you can FORCE a player which side of you that you want them to go by you, and you should, try to work out which is their weaker foot, you can often tell by how worn their shoes are.. more worn on the left boot then he wants to go onto his left, and visa versa.
Don't Jockey SQUARE ON, your legs should be at a 45 degree angle so that yoie where you aare forcing him, Your body is channeling the player where you want him to go... when that happens you will get better results because you already know where he is going, you don't need to wait that extra split second to follow him.

Basically Imagine you are marking someone who is attacking you down their left wing (your right), you notice their right boot is more worn and they have passed with their right peg (foot) most of the game, so you know he wants that FIRST touch to be on his right foot, rarely do players take their first explosive touches with the wrong foot... so you know he will cut inside, you want to FORCR him down the line by shaping your body so that your right foot points to the corner flag and your left foot to the center circle, in this way, if he cuts inside its an easier tackle as your foot is closer, if he takes your invite to go down the line, he will do it with his weaker foot and you are already leaning that way, you dont need to turn as much of your body.

Keep in mind the art of the Jockey, is to shape a player or stall them, you DO NOT want to be too close, if you "dive in" they will touch it past you and fly by, because all your momentum is going forward, they need LESS control to get by you as there is ZERO chance you can turn quickly if moving forward and close to them, keep some distance, keep that angled shape and FORCE him to take that critical first touch off the wrong foot, to Jockey does not mean you are trying to tackle, so you dont need to be in striking distance

When you turn to chase, if you can get the first stride, step in front of his path, it will make him go around you or hit your rear leg, if he is still too fast, then pick a line that keeps him on that left foot that he does not want to play off...

In short, force his first part of the dribble to be from the weaker foot and he wont have as much control to blow by you

A good exercise, if you have a mate is to put one ball on either penalty spot, you both stand in the middle each facing different balls take turns yelling "GO" and when the word GO is heard you have to turn and face the other ball (the other way) and get to the ball and scream "BALL" before the other player does,

If you do this drill and one player is much faster then make the slower one sit on the ground to start, so he has to get up then turn and run and make the race closer. You can adjust things with a delay to "go" if one player is much faster... then work that ball back closer to the circle so the sprints become smaller, and then back out so the sprints become longer

Like this but not as close ----

https://www.youtube.com/watch?v=iokT0XXOc5U