*Every woman's labor is different*

That being said, I can tell you how mine felt.
I was induced right at 36 weeks-exactly where you are.
The first contractions felt like really bad menstrual cramps. Then worse and worse.
The back pain didn't come until I got my epidural.
Have you already lost your plug? Has your water broken yet?
How often do the cramps come?
I would start timing them.

oh no, the chances that you are in labor are slim.... Baby will come out when baby is ready, it is probably the head descending into the pelvis, or the baby might just be very comfortable in the place that he or she is in I.E: right on your sciatic nerve. I had this prob a lot with all three of my pregnancies and the best thing I found to do, is get on all fours and rock back and forth. you kinda gotta coax the baby to move sometimes. If your worried about the lack of movement, try drinking some ice water, wait a few and if still nothing, try putting an ice pack, or a frozen bag of veggies directly on your tummy, where you think the baby is, this will get them to move, so you know that they are ok. Other than that, something else you can do that helps elevate the back pressure and pain is: Try leaning on the back of a sturdy chair, or the couch, and sort of let your tummy hang and make sure NOT to lock your knees. in the last trimester it seems to help me keep a lot of pressure off of my hips. Good luck and I hope this helps

it sounds like the baby has hit your sciatic nerve. that would be the pain in your leg. the pain in your hips and lower back is your body preparing for labor! your body releases a hormone called relaxin, and that is what helps the bones and joints loosen to prepare for the baby comin through!! expecially if this is your first baby. its all normal pregnancy pains...nothing to worry about...you will know when labor is in effect.

Depending on the way the baby is laying before delivery can very well have an affect on where and how painful labor can be. Let's say the baby has not turned and it is facing it butt toward your back. You will most likely feel most if all of you labor in you lower back. Some babies just do not enter the birth canal the way that should. Like in "Breach", they can try and trun the baby before birth but, many times if it has already "Crowned" in the birth cananl, that is not easy to do and the may have to do a "C". What you are feeling is back labor. Only "Brakston Hicks" and the baby is facing the wrong direction and just getting ready. Needless to say, if you break water, go right to the hospital because chance of a "dry" birth will sometime occure even in a normal delivery. Better safe then sorry either way. Normally there is no harm for the baby, just a different approach to the delivery.
Also, there is what we call a bloody plug. This is a mucusy type of blood tinged stuff. If you see that, that means usually that labor is not to far off.