Since you are on your 6th pregnancy, your ligaments aren't what they used to be. This means that they aren't holding your uterus up like they used to. The weight of your uterus can cause a lot of pressure. I recently gave birth to my 6th child and I had a lot of pressure for the latter part of the pregnancy. It's completely normal and doesn't necessarily indicate anything will happen early.
As for Braxton Hicks, with this last pregnancy i started getting them early in the 2nd trimester. It's also normal.
Braxton Hicks are fairly common from this point - you've been 5 times lucky!
It also sounds like bub has dropped into position, which I'm told can happen a little earlier for women who have had previous pregnancies. Sometimes they have very little fluid ahead of them with most of it behind them, so they sit a little lower. I'd mention it to your midwife or OB, but it doesn't sound all that unusual for your stage... just unusual for you!
a friend who recently gave birth described something similar, but she was like that for weeks before anything actually happened..although bubs came a little early!