If you just tacked on something to the existing board then it is no surprise that you didn't see any improvement. An antenna has resistance, inductance, and capacitance. It is a complex circuit. It may look simple but it is not.
The ESP-07 has an on board antenna and a connector for an external antenna. To use the external antenna you should be removing the connection to the internal antenna. The shorting 0 Ohm resistor next to the connector is what needs to be removed.