I never had regular periods I am 24 years old made an ultrasound shows that my uterus size is small 4.4 x3.3x2.3, so worried, how this will afect me?

Small uterus. Small uterus in and of itself it should not be a major issue to pregnancy. The uterus does grow with pregnancy and you will be observed.The irregular periods should be evaluated. Did the ultrasound note polycystic ovaries? , consider thyroid, prolactin, and androgen studies and endometriosis eval. Follow up with a fertility specialist. Good luck.