Ugh Soundfonts lol
Here's a good example of beginner's lack of knowledge in the art of proper mastering. You can hear this when the bass drum hit's and momentarily drowns out the rest of the music. I was like this once... and unfortunately still am... :)
Soundfonts are ok for mock ups but you should really go for proper sound libraries even free one's (Namely EWQL, Vienna, Native Instruments etc)
If you msg me I'll send you a link of the ones I use (some of which are free)
Also you should be looking to add MANY more instruments, in fact what would be a good basic addition to this one would be lead and bass guitar (a little bass goes a long way).
Don't worry tho, everyone's been here before many of which also can't compose to save themselves. You have talent all you need is sounds that can keep up with that creativity.
Peace Out!