frustrated and upset

my fiance and I have only been ttc for about 3 months now and still no luck.

so i have a little sister who is 3 years younger than I. im 28. she has a 6 year old daughter, a 3 year old daughter, a two year old son and is currently pregnant. now i would be so over the moon for her, if not for the fact that she lives with my parents, whom I pay 50% of their bills because they are know income, and she has no job. she dont get child support, no state assistance, and my disabled mother has all 3 of her kids 24/7 even when shes home. her current boyfriend is an alcoholic and my pregnant sister takes off every weekend to go to the bars n to partys with him.

when I found out she was pregnant, I could only think how is this fair?! shes already got 3 kids she dont take care of, even has endo and here we are, trying to get pregnant and we havent yet. I feel so bad for thinking this way, but i just cant help it.

Im sorry if you dont feel my pain. I just need to vent to someone.