I'm another mom dealing with a thin cervix and conractions, not a midwife. But in my opinion and experience, I wouldn't fool around with this. If the pressure/cramping are causing your cervix to change, that IS preterm labor. If I was you, I would talk with your midwife about going into the hospital over the weekend (like right away!) to get a perinatologist or high-risk ob involved. Or if your midwife really doesn't think this is a big deal, I would find another midwife! What you are describing is not normal. You could probably also call the labor and delivery unit of a local hospital and explain what is going on and see what they suggest.
When I was 32 weeks pregnant with my first pregnancy, being 1 cm dilated and partially effaced meant drugs in the hospital until the contractions stopped and then strict bedrest and medicine at home thorugh 36 weeks. With my second pregnancy, I began to feel contractions at 23 weeks. This time I was seeing a midwife and planning on a homebirth, but she also did not take it lightly. At that point, my cervix was still long and closed. We managed things at home (rest, water, suppliments and herbs) through 30 weeks, when I lost my mucus plug and my cervix was changing enough that we brought in a perinatologist for consult. I again spent about a month on bedrest and medication before my son was born at 35 weeks in the hospital. Though he was close to term, he needed a little help in the NICU.
I'm pregnant again, just about 20 weeks this time. As a result of my history, we knew I'd be high-risk for preterm labor again, so I began to see a perinatologist along with my midwife at 8 weeks. I began to notice contractions at 12 weeks and since then have been seeing the perinatologist and midwives very frequently (at least weekly, plus anytime I feel an increase in pressure or contractions). My cervix is still closed, though softer and shorter. I'm still having frequent contractions and I am on medication to stop them. I'm guessing that if I was in your situation (dilated at 24 weeks), my midwives/doctors would have me in the hospital and would be doing everything they could to make sure that labor did not go further.