Waiting for lawsuits only makes lawyers money.

Register your catalog with the copyright office as it's only a one time expense (I believe around $50.00) then as you write new material you can just add it to your catalog.
This is good as in this biz volume of production matters.
A&R folks don't spend a lot of time just "carefully listening" to a specific song. They spend possibly about 15 seconds then move on to the next submission as they are getting thousands of submission per day if they are a large successful org.
They also troll YouTube, and other sites. So...
If they see consistency, and lot's of songs they can get a better feel for the artist. The large volume says to them that you are producing. In other words lot's of possibilities to make their client money.
It also shows them work ethic...you are putting time in each and every day making new material. This matters as if they do like your submissions and they do well for the client's requirements, that means instead of trolling for new...they are calling you back for more.
Think about it...while we all want to receive our Performance Rights and sync rights royalties...sometimes a given song that maybe you might not be crazy about, can generate a ton of ad revenue for you as a make up for the other songs that may not be "Killing It" on the royalties side. A balance.
Also, with your catalog registered in the copyright office, if someone does try to pirate your intellectual property, instead of doing a "Take Down" or a bunch of letters back and forth, you can go straight to "Hey man, this song is already registered with copyright office, let's make a deal." After all if the pirates biz is generating a ton of money, wouldn't it be better to just negotiate the price in royalties for usage and leave it up and running? It is after all your income.
Perfect example of this is a Little Feat Song called "Let It Roll." release back in the 80's I believe. This band while hugely popular with it's fan base has always had problems with labels not doing enough to keep the energy alive. They released the song, it was a minor hit on radio for a bit but died like a lot of their other songs. BUT... it was picked up by a whole slew of Cable Networks for their original films. (lifetime, and others) so they wound up making a lot of royalties from the sync licensing for the films that were being broadcast everywhere on the different (and often separate networks) channels via cable.
So always do the copyright. No one likes law suits except lawyers.