RadioRon's information is good.
The antenna if very important. Your 7 meters high antenna is not good. FM is "line of sight". If you stood at the top if your antenna you will only reach as far as you can see. My smallest radio station had an effective power of 20 watts. 10 watt transmitter and a 2X antenna. It was on a hill on the top of a 7 story building + 60 feet of tower. With the hill the total height was maybe 200 to 300 feet. We had OK reception at 3-5 miles and at 10 miles we had complaints about the signal.
Then I upgraded to 20,000 watts. We had many listeners at 30 miles out. There was a town 60 miles away. They could get us only if they put an antenna on top of their houses.
My biggest stations had antenna with gains of 12X and towers of 600 to 1000 feet. A 100,000 watt radio station may only have a 10,000 watt transmitter.
Earlier some one mentioned directional antennas. In FM usually the same power is sent out in all directions. (North/South/East/West) A antenna with a gain of 1 sends power into space and into the dirt. It sends power out parallel to the earth at 1X. A antenna with a gain of 4 will send much less power up into space, and down into the ground. It will focus more power at the horizon. There are no people in the sky listening to your station. The people under your town do not want a VERY strong signal. A good antenna does not sent power at the people near the tower, it focuses the power at the radios miles away.
Your antenna location (height) is the most important thing. Next is antenna gain. Many radio stations have the music in one town and the transmitter in a different town on top of a mountain.