I'm 25 & keep losing weight & have problem gaining. Now I'm only 38kg. Can this 1 of the reason why its quite hard for me to get pregnant?

Yes. Low weight can stop your brain from stimulating the ovaries but is in the absense of a period. If there has been a negative w/u for your weight, a drug called Mirtazapine is cheap and helps with sleep, anxiety problems and weight gain. You may not eat secondary to anxiety, if so consider that one. Good luck.