Irregular period? Is it normal?

My last period was on June 9th around there

And it only last for 4-5 days

The flow can be light or light to medium.

My period is so random it can come a month after, two months, 3 months.

And yes, I had protected sex on July 15th and he did not even finish. I even took a pregnancy test, but nothing showed up

So can sex mess up my cycle even more ?