Well I had a sweep and heaps of nookie before I had DS and neither worked so to your doc LOL.
The thing I tried that I really noticed was doing "something" was nipple stimulation. I used to do a few sessions on my breastpump a few times a day and that would get some pretty ouchy BH's/contractions happening. I started loosing plug when I started this as well - could've been coincidence but I was definitely getting contractions.
If you have a breastpump it can't hurt