What target would this assocate with if you actually had to fight someone?
Bottom of the elbow?
Yes you have a flexibility problem since you can kick a pad like this...
So bend your toes back at a 90 degree angle or more to your foot...
But most of us humans can not.
(It's Wednesday and sarcasim is running amok)
Yes, this is a simple law of physics taught with vectors in physics 101.
(All MA's should be required to take physics 101)
There was not much power in what you did because there was no support from the body.
Your hips are your center of mass and where all your power comes from. Your hips are supported by bracing yourself against the earth (How your legs connect with the ground - cause the ground is big, no, I mean really big

)
So when beginners throw the kick they usually swing their leg foreward
and then the knee which is the piviot joint usually stops (major important point, stopping the knee is the problem) and the kick goes straight up. Now 9 out of ten times when people kick like this they don't transfer energy from the body motion to the leg. - like snapping a towel.
Therefore not much power as you are only using your calf muscle only.
Targets like groin, pelvis, liver, spleen, sternum... are vertical, not horizontal. And the most power you can transmit is if the ball of your foot travels into the target at a 90 degree angle (parallel to the ground).
To prove this, just go hit a heavy bag with your front kick and yoú'll get the point.
So in a front kick you need to raise the tool (ball of foot) to the height of the target. This means that the knee will be higher than the target (this is a lot of leg work which usually only a good instructor will force you to do). Then as you kick the knee drops down. So if done right it will feel like you are kicking down.
Another way to look at it is:
What if you could go into a dark room with a black light and paint the ball of your foot white. Then watch how it moves. The only way for it to go out is if the knee moves. That is what makes the kick go straight into the target.
Now remember the base?
When you hit something heavy like a heavy bag the supporting leg must be angled toward the target. If not you go flying.
When hitting a pad, not so big a deal.
Spend as much time as you can practicing the first four basic kicks.
Front, side, turning, back.
As how well you can do these will determine the rest of your career.
All other kicks are a variation of these.
There is much, much more than this but it is a good start.
Contact me in the future after you've worked on it.
Saludo,