Reciprocal Relationships and Bridesmaid Duties

I'm getting married this year in August. I'm one of the last of my friends to get married, and in the past I've stood in quite a few of my girlfriends' weddings as a bridesmaid. I've also planned 4 bachelorette parties as a bridesmaid. As a bridesmaid in my friends' weddings, I've attended every bachelorette, bridal shower, and made it my mission to be the last bridesmaid standing at every wedding I was in.



Now that it's my turn to get married, I'm finding myself super disappointed in some of my girlfriends. For some whose wedding I have stood in and even thrown the bachelorette for, they aren't coming to my bachelorette at all. I have a few friends that can't make it for appropriate reasons, like just having a baby. I completely understand that. I sent out the date 6 months in advance, and made sure the party wasn't super expensive or far from our home base of Chicago. I've gotten a few really lame excuses like "oh I may work that weekend" or some "no" responses without excuses at all.
I can't help but feel disappointed, maybe in myself because I expected things to be reciprocal when I got married. I felt like I out so much effort into making their day special when it was their time. These are friends that I felt close with, that I continue to maintain relationships with. Anyone else over-evaluating their friendships during wedding planning? I'm now so bummed by a few girls that even though I was going to include them in the wedding party, I think I won't invite them to be bridesmaids because they haven't shown any support.