Your priorities are all screwed up here.
You can have a wonderful time with your bridesmaids and a fabulous wedding without requiring people to be in hair and makeup at 6am like they're a stonkingly well paid Hollywood actor getting ready for a long day of filming for the latest Marvel movie.
I actually did focus a little too much on what the photos would look like at my wedding, to the point where I asked my husband's female friend who was a witness to wear certain colours to match the rest of the wedding party, who were all either bridesmaids or men with a tie in the same colour as the bridesmaids' dresses.
Well guess what? My photographer was having a really bad week because his best friend had just died and the photos were a bit shit. That one photo with all the witnesses that I was so focused on has my annoying aunt in the background wearing a fluorescent pink monstrosity and we never successfully managed to photoshop her out. The photographer didn't even get any decent photos of me and my husband, to the point where, a year later, we decided to hire another photographer to do some shots just of us and I paid hundreds of euros to get my hair and makeup done again and put the dress back on and we had some couple photos taken. And even after all that we still haven't got round to doing our album.
But also, guess what? It was still a fabulous wedding, we are happily married, I had a wonderful time with my bridesmaids, and nobody was required to be at my beck and call at 6am.
The bride who is paying for everyone to get their hair and makeup done at the crack of dawn isn't doing it because she's a kind hearted friend who is giving her bridesmaids a special treat. It's because she wants the photos to look a certain way. And whilst we all want to look lovely on our wedding days and for there to be beautiful photos, that can't be guaranteed. The bride herself might fall down the stairs and break her leg, or have an allergic reaction to something the day before the wedding. It might piss with rain all day. A guest might puke or spill red wine all over the wedding dress within minutes of arriving at the reception. The photographer might be in a car crash on the way to the wedding and not show up at all.
Trust me. The OP being on duty at 6am is not going to make or break this wedding, and any bride who had not lost her goddamn mind in the run up to her wedding would realise that her pregnant friend's health and comfort, and their friendship, are more important.
The wedding industry has a hell of a lot to answer for. The bride is not Kate Middleton (who apparently did her own wedding makeup anyway) or the new monarch being crowned. This event is not going to be televised and watched by billions of people around the globe. She is just a regular person, getting married, and nobody other than her very nearest and dearest actually cares that much about any of these details.