Cynthia, please leave your question in one thread.
If you have a Fishman in your adjustable bridge it might be a Full Circle.
This pickup has a huge output signal (voltage) and needs a medium high input impedance on the input of the first connected electronic device. So it depends on the device input you connect your pickup to if you need a preamp.
Make sure your bridge is not angled to either side. The contact surfaces of the bridge to the Full Circle need to be very plan. If you did the exchange of adjusters yourself, you might have uneven surfaces that should be corrected. If a luthier did the install, you might want to ask him if he planed the bridge surfaces AFTER you checked the electronic connection with us.
If you have a BP-100, you need a preamp with at least 10 MegOhms input impedance, like a Fishman preamp or Francis Decks HPFpre. Both could be used with the Full Circle too.
A BP-100 not well installed could result in a weak and bad signal. Just a few bass players are happy with this pickup.