It's really tough, isn't it? I developed Pelvic Girdle Pain (aka SPD) in week 14 of my twin pregnancy. I'm in week 28 now and unfortunately, the pain is getting worse. I would recommend you speak to your GP to get a referral to the physiotherapy service in your area. I did speak to my midwife about my pelvic pain initially, but she told me to speak to my GP.
I've had a course of physio and have just been told that if I was going to see an improvement, it would have happened by now, so I've been referred back to the physio team. I've had a real wobble about that, as it is really difficult to see how I can get through the next ten weeks or so of my pregnancy when I am in so much pain.
I think a belt can be useful, but the basis of my physio appointments have been to do specific exercises to strengthen my core muscles. I think that will be really useful for you. I know you've said you are doing pelvic floor exercises, which is great, but it won't help with the pelvic pain you are experiencing. Targeted exercises will be able to help strengthen your core. I don't think it will hurt to see a chiropractor, but in my experience, I've never been given exercises to follow in between appointments. Whereas a physio will be able to do that.
A few things that I have found to offer very temporary relief are using an electric heat pad for 20 mins or so at a time, and using an ice pack can also help. I keep a pillow between my knees when I sleep, as that can help a bit with the pain. Sit down to put trousers on, etc, and make sure you have weight evenly distributed on both legs when you are standing. Doing things on one leg will just exacerbate the pain.
I am disabled and I already use crutches inside the house, and a wheelchair outside, but it is possible a physio may recommend crutches to help you in moving about, maybe a wheelchair too if needed. Please don't try to do too much, or push through the pain. That is not going to help at all. You need to rest.
If you speak to your GP, they may also be able to prescribe stronger pain killers to you. The ones I have do help to take the edge off the pain, but it doesn't go completely. Still, it's better than not taking anything at all. Please reach out to your GP to access physiotherapy.