When you break, you need to control the cue ball. Simply slamming into the balls is not the right way to break. You want to hit the 1 ball square and have the cue ball pop back into the center of the table. The center of the table offers the best chance to have a shot at the 1-ball. Also, there is no pocket at the center of the table. The pockets are all along the rail. If you control the cue ball well after the break, the cue ball should not go anywhere near a rail.
When I say hit the 1 ball square, I don't mean hit the exact front of it. I mean that you want the cue ball to go straight into the 1 ball. If you break from the head spot, then yes, you will hit the 1 ball at the front. If you break from the side, you will hit directly into the 1 ball. The advice piglet gave above is 100% correct. Aim at the point where the 1 ball hits the felt. A good friend of mine (Tony Robles) gave me that very same advice a long time ago when I was moving up on the pro 9-ball tour. It helped my break a lot.
You said that you break from back by the head rail. You said that you can't break from the headstring with a normal bridge. Well, if you can't do it, practice it. You will break much better. The extra distance will kill the power, especially if you are playing on 9-foot tables. On bar boxes it doesn't matter much. When you practice, break from the headstring. When you are competing, break (for now) from where you are comfortable. Eventually you will learn to break from the headstring and you will have better results. A long time ago, I could never break from the corner. I got sick of people breaking from there and making a ball against me when I couldn't do it. What did I do? I learned how to do it. That is what you have to do. Learn how to break from the headstring. Don't get discouraged if it doesn't work immediately. Keep trying during practice. Eventually it will work for you.
Also, you need to control the cue ball. If you break and the cue ball goes flying off into the rail and running around the table, you didn't hit the 1 ball square. Here is what you should do. Take about 50% off the power you use to break. Hit 'em lightly at first. Try to hit the 1 ball square and get the cue ball to not hit a rail after the break. If the cue ball gets kicked by another ball into the rail, that is okay. Try to see if the cue ball would have hit a rail if it wasn't kicked. Keep doing this and as you get more consistent at it, slowly increase your power. Again, only do this in practice. Eventually you will be hitting the balls at about 80% of your maximum power and controlling the cue ball regularly. You never want to break at 100% power. 80% is plenty. If you hit the 1 ball square, you will see the balls scatter. That is the key, not trying to blast them.
What english do you put on the break to get the cue ball to stop near the center? I've seen a lot of posts and heard a lot of teachers telling their students you have to hit 1 tip of this and elevate ## degrees, etc, etc. I would not listen to any of that. Don't get me wrong. I'm sure what everyone is saying works for them, but that is my whole point. It works for them. It may or may not work for you. You need to find your own spot that will get the job done. With my stroke, I break from the corner, have the cue elevated slightly (due to the rail), and hit about 1/2 to 1 tip below center, depending on the playing conditions. You can try that if you want, and if it works, I will be happy that I helped you. However, your stroke is different from mine. You may hit the cue ball with 1 tip of draw and get a lot more draw than me, or a lot less draw than me. I don't know. Use the advice others (and I) give as a starting point. If you try hitting it with 1 tip of draw and you draw the cue ball way back to the head cushion consistently, hit it with center ball.
Anyway, I hope all of this information helps you break the balls better. Good luck.
Andy Segal
