How do I cancel my contract with a real estate company before the six month expiration date

Your listing agreement would be the first place to go to find out what your options are for cancelling.  You can probably cancel at any time but you might owe them a commission if you ink a sales agreement before August.  You might also complain to them and get them to start getting you more activity.  Their effort isn't all that gets you activity --some of that is on the desireability of your home and what you've done to make it presentable.  Sounds like you need some dialogue with your realtor.