Could i be in labour?

been losing my mucus plug all day, irregular contractions lasting 60-90 seconds, very painfull and belly goes real stiff, real bad backache, unbearable pressure inbetween my legs and finding it very difficult to walk, had nausea and sickness for the last week and started having loose stools yesterday (tmi) i knowI am having a homebirth so was wondering should i ring the midwife yet? im 40 weeks pregnant wityh first baby