I feel like I'm over reacting but feel I'm right

So back story my brother married my sister in law 5 yrs ago and I really liked her , I'm the little sister and I have ALWAYS been hard on the girls my brother has dated ! Well this one came along and well they dated for 3-4 months before I was allowed to meet her lol ..which is fine but once I met her I loved her I thought she was perfect for my brother ..well fast forward now 6/7 years and we'll things have changed

Add a son for them and a daughter for me as well as a I am married going on 4 years .. well our kids are only 4-5 months apart ..they are 3 going on 4 and 2 going on 3 next month ..

Well now we are pregnant at the same time again!! She is 7 weeks further along then I am , I am 18 weeks today and she's 24/25 weeks .. she's having a girl and we are having a boy ..

Well my rant is is this and someone tell me if I'm off wrong or just hormones going crazy !!

So ever since we have been trying to concieve I feel like it's been a competition for her ..like she always wants to be pregnant before and checked to see if I was and we weren't. I just figured it wasn't out time . Well when we got pregnant it was like we were so excited !!! Well when we told her it was like all we got " great congratulations" and then she just jumps into to her pregnancy everything is about HER! And HER pregnancy !! So I let it go for a few months well recently we found out we are having a boy!! And we are so excited well I let her know and all we got was ". Loved image" and then she goes into her " I can't wait to hold my baby girl and she's gonna be perfect " and I'm like wait a second !!! How the hell is it ok to just jump on my happiness and my excitement about OUR ANNOUNCEMENT ! Like I get it she's excited but when she posts things or talks about her pregnancy I have NEVER wrote anything about our pregnancy bc it's not my place it's about HER ! So why is it ok for her to just go on and on about her when we are talking about my pregnancy ?? I feel like it's self centered and unnecessary and I've grown to the point that I don't even wanna talk to her ! Bc I'm so irritated and over it . I can't stand how self centered and narcissistic she is . She's self absorbed ! Am I over reacting or I am right ?