Bluetooth audio problems on a MacBook
The best step to isolating your issue would be to collect some data about the bluetooth environment where you are using your mac. Radio waves come and go with other devices, new phones, degrading antennas and changes in bluetooth firmware.

The Bluetooth Explorer is the best tool I have found to troubleshoot bluetooth hardware and data. It's free as part of Xcode from the Mac App Store.

You can debug data issues, see the protocols that connected devices are using, and get to all manner of engineering data relating to bluetooth such as errors, relative signal strength indication (RSSI). It's hard to tell if this will help you, but it lets me know when a microwave or home phone was causing noise issues on several occasions when my hardware was otherwise working properly.