i saw an osteo a few times during the third trimester!! all perfectly fine, id recommend seeing an osteo over a chiro though and maybe look for someone who deals with pregnant women
i see a chiro regularly - but he works in conjunction with a myotherapist, and also practices physio, accupuncture etc, so he calls in whatever skills are needed at the time. i think your best suggestion is definitely to see SOMEONE - and when you ring to enquire, ask how often they work with pregnant women.

i've been seeing my chiro for 13 years, and he has adjusted treatment for me depending on where we're at (ivf treatment, pg etc) so i know he's the right one for me, and would recommend him to anyone - and usually do! not a lot of people out here to recommend him to though