If you choose chiropractic, you should have a chiropractor experienced with pregnancy, and you should be prepared for a number of visits. Hopefully you can find one who sort of limits the visits, in the sense of suggesting that, if 5-6 visits doesn't take care of the problem, he/she needs to do something different. You don't want to expect a miracle in 1 visit, but you don't want someone saying it's so open-ended that you'll be going for a year!
You also might want to check into chiropractic techniques - they vary by practitioner. Personally, I was not interested in someone who was going to do a lot of cracking and sudden snapping of any part of my body! Applied kinesiology and similar techniques are, in the minds of many, much safer.
Also see if you can take your X-ray with you so you don't' need additional exposure to radiation, particularly because you are pregnant but I'd say that for anyone. You have paid for that X-ray, so technically you own it, and your primary care physician should make arrangements to release it to you with signed release papers. If it can be sent digitally, so much the better.
Sciatica can be tricky - I had it for many years and it was awful. There are some exercises that can help but I did not get much relief that way. The chiropractor I saw did help me, but not all that much. I still had sudden shooting pains that would stop me short, and I was worried about falling and driving.
I got limited results from chiropractic, even from someone who seemed committed to my care. He also gave me a lot of expensive supplements to help this as well as overall immunity. I thought I was doing the right thing for my body, but looking back I can't say there were measurable results.
I got all my results from cellular nutrition where the food scientists do all the work and where clinical studies are involved. I stopped using products from companies that didn't manufacture their own products and just farmed it out to other countries where there are even fewer regulations than in the US. I've gone to conferences and seminars, and I've talked with many people who had great results from a whole variety of similar ailments. I learned about nutrient absorption (vs. what you actually swallow but don't absorb), and I now understand why the things I did for 15 years didn't make the difference that I see now. I've had NO sciatic flare-ups for over 5 years now, so I know that this works.
There is tremendous work on cell repair and anti-inflammation - I just went to a seminar last week with a chief scientist in this field, and I'm struck by the clinical data they use to ensure safety and effectiveness. That's an added benefit that wasn't even available to me when I started, but I'm certainly employing it now. I also like that this approach is save for pregnant/nursing women and children and is used world-wide in feeding centers and clinics.