Contractions? Tmi

At 34 weeks and 3 days I found out I was 3 cm dilated, long and thick, baby still high up. Today I had my 36 week check up and she said i was between 3 and 4 cm dilated, long and thick, baby still high up but my cervix is now soft. When I went number 2 I felt a lot of pressure and sharp pain coming down from my lower back, ever since then I feel it when I'm sitting up with tightness in the front, I was wondering if it could be contractions in my butt? I know the tightness in the front are contractions. I just don't know if you can feel them that low in your butt/back. My first time ever feeling it! Thank you!