Fleecy (and others) have you been to this site??
www.pelvicpartnership.org.uk/
Yes your hormones are making your ligaments lax - BUT - with PGP/SPD there is nearly always a physical inbalance that is causing/contributing to the pain.
If you have a stiff muscle or a stiff joint this can put uneven forces on your pelvis. This doesn't matter if your pelvis is not pregnant and is acting like a nice solid block. When you are pregnant you pelvis starts acting like two halves instead of one block. If everything around it is nice and even - fine and dandy - if not, the uneven forces cause one half of the pelvis to move relative to the other - causing you pain.
This means if you massage/ stretch/ relax the stiff muscle; or mobilise/ gently loosen the stiff joint - you will reduce the forces causing the relative movement.
Some sort of MANUAL therapy is nearly always beneficial - be it chiro, osteo or physio. If you are lucky enough to be able to afford it I would go private straight away. Either way get your GP or midwife to refer you to an obstetrics physio/ womens health physio.
Print information off the pelvic partnership site and take it to your physio - they shouldn't be saying "there is nothing I can do it's hormones".
I went to a chiropractor - one of my sacroiliac joints (pelvic joint kind of above your buttock) was much tighter than the other - he mobilised it and I have had a massive improvement in symptoms.
I am lucky I have it relatively mild (at 18 weeks). It came on at 13 weeks, and I really wanted to nip it in the bud before I got bigger.
I get really bad sitting down at work - so I have put my computer on boxes and started working predominantly standing up (though standing exacerbates symptoms in some people).
I also found stretching by bum muscles really really helped. If your symptoms allow you to, sit in a chair and rest one ankle on the opposite knee. Let the knee fall to the side and lean gently forwards to feel stretch in your bum.
Sorry for essay like post.