Are my worms doing what they're supposed to?

I've been keeping an eye on my little worms in my wormery purchased in March this year. At first seemed very small but wriggly and I had high hopes they would grow into compost munching monster worms. Only have the sump and one tray for them and was pleased to see fatter worms as time has gone on with not too much prodding to keep them happy. Read about them escaping into the sump occasionally and have been very careful about emptying it to avoid any drowning accidents but so far all have kept in the tray. Til now. Yesterday about 30 of them were in the sump lovely looking big worms which should have been making compost. I re-did the bedding and carefully moved the worms back into the tray. Later, even more were in the sump getting up close and personal and I didn't disturb them. When I went to show my OH a couple of hours later there were only about half a dozen in the sump. I'm thinking of adding a second tray in case the first one is becoming overcrowed. Also worried about where the offspring will be born. Google is getting too intuitive - had some interesting searches come up after googling the mating habits of worms. Any advice gratefully received.