My period is irregular, I did 2 urine home tests they gave me a positive result then a blood beta hcg was positive but it was low what does this mean and why does this happen?

It may just be early in the pregnancy. There is a wide range for hcg levels. What matters most is that the level rises, so if they are at all concerned, they would schedule another blood draw within a few days time. If that wasn't mentioned to you, then they are not concerned.

Thanks a lot and that what happened really I did it again and it shows increasing so pregnant now

Good to hear! Enjoy the pregnancy journey... hope it's smooth and easy for you!