Maid of Honor Speech Anxiety

My sister is getting married April 30th and I'm freaking out over my MOH speech. Any suggestions on how to minimize the emotional breakdown?

Here's a little back story to explain where my emotions are:

I'm the 2nd of 4 kids. All 3 of my siblings are married and have kids. Between them, I'm a proud aunt of 7!! My sister was 7 months prego when she got married through the courts. After 2 1/2 years and 2 kids, she's finally having an actual ceremony and reception to celebrate with family and friends.

I've always wanted to get married and have lots of kids, but I'm not the best judge of character and so my relationships haven't been very healthy. Over the last 3 years, I've struggled with my emotions. My head knows I'm still young and have plenty of time. I'm only 30. ...but you can't always control how you FEEL. Especially when all 3 siblings were prego at the same time at one point. I really felt left behind.

I've come a long way in the last 3 years and most days I'm the happy, bubbly person I've always been... but every once in a while I have my complete meltdowns when someone asks when I'm going to get married and have kids, or tries to suggest ways for me to meet someone.

I'm not a big fan of public speaking to begin with, and I know I'm going to cry when I give my MOH speech, but I'm nervous I'm going to become a blubbering mess if I'm not careful.

Any suggestions?