Help announcing pregnancy to sister

I am 15 weeks pregnant and have 2 siblings. We have told our immediate family members on both sides except my sister. She is in her late 30s and single. She was really into her career and never really dated, maybe a few dates here and there but no boyfriends or even flings. She is just really awkward at this point in her life when it comes to the men and dating, which as you get older it becomes harder anyway. She has always wanted children so SO badly and anyone ttc knows the feeling when someone announces they're pregnant and you're happy but sad also.

So our brother/sister in law have 2 children and she was happy for them, but very sad and jealous inside. She got through it and is a wonderful aunt. Now Im the youngest child and cant figure out how to tell her. I know she will want to be happy but I know it will hurt her so much at the same time. Now we planned this and decided our happiness wont let her reaction get us down at all but she's my sister. Since she is the last to know before we announce it to relatives and friends and Im slightly starting to show, it needs to happen soon. Sorry this is so long. Any advice is greatly appreciated, thanks