Braxon hicks are where your stomach gets tight then releases, they shouldn't be painful, just uncomfortable, irregular. The real contractions are painful and stop you dead in your tracks, become more intense and more frequent.
Well I'm 39 weeks due Saturday and have never had bh's. I have had period like cramps. I just last night started to have contractions but in my back! Some women don't get bh's but you will know when you have contractions they hurt like heck and you can barely move sometimes breath! I wouldn't worry about not having them just yet or having bh!