Do I Need A Filter?

In theory at least, the order should be:
Antenna - LNA - Filter - feeder - receiver.

Then come the “if’s” and “but’s”

eg. if your feeder is good quality (eg. including the plugs and sockets) and short, it doesn’t matter much where it goes.
or if you are very close to a noise source (say 170m from a 4G cell), you may find you need the filter before the amp.
but if your range is geographically limited (eg. surrounded by mountains), you may be better off with a filter and no amp.