Happy but very sad as well

Today my sister told me she's pretty sure she's pregnant. Don't get me wrong I'm super excited to be a aunt again. I'm super sad tho because we have been trying on and of for five years with two misscarriages and a still birth. I swear I'm a dud. My sister got pregnant with my nephew with a one night and on the depo and this time she will be on the depo Again. Is it wrong I'm feeling blue?