My fiance and I got engaged about 2 months ago and have set a date for next summer. My twin brother (who lives in the same city as me) just proposed to his girlfriend, who I have already asked to be my MOH. I had been told they *might* get engaged at the end of the year around the holidays, which I was comfortable with as it would have given my fiance and I 5-6 months to celebrate with family and friends and plan independent of them before it became a family affair. We are the only siblings and as you can imagine, quite competitive being twins and having to share every moment and milestone our entire lives has been really difficult for me. When I asked his girlfriend to be my MOH I assumed we'd have some time to plan my wedding together before transitioning over to hers. They now want to have their wedding immediately after ours in 2021, which means we're planning on the exact same timeline.
Of course I'm so happy for them, but can't help but feel disappointed and frustrated that now we're doing everything side by side and my fiance and I don't have this moment for ourselves. The entire year will now be about "the twins getting married" instead of a special and unique moment in my and my fiance's life specifically (which obviously it still is- just not ours alone.) Our family lives all over the country and will have to travel for the wedding, and I'm now concerned that not only is it inconsiderate to expect 2 back to back trips for a wedding in 2021, but not everyone may be able to come and may now have to choose which wedding they want to attend. I also now can't imagine why my MOH would even WANT to help plan and be involved with my wedding and continue to focus on ideas and plans for me, when she will need to plan her own, which will of course take up her attention and focus and excitement- as it should. She's too nice to back out but I'm worried she'll just continue out of obligation and I need to give her an out. I'm frustrated and hurt that my brother didn't communicate his plans to me and that this didn't even cross his mind as something that we might have concerns about. I don't see what good it would do to bring it up now and don't want to harm any relationships, so just feel that I have to get over it and fake my way through it. My parents don't seem to understand and think I should just be excited we get to "go through this together". I'm also frustrated at them that they didn't say anything to him in advance or help him realize this might have been something to consider and that maybe I want to experience this milestone myself.
Looking for honest feedback and advice on how to navigate this? I realize I may be acting slightly selfish, but also think my feelings are valid given how intertwined our relationships are.