Awww your little one's are so cute Emma.
I have seen the eggs within the female P.Cheni's a couple of times. They have to be in a cooperative mood and on the glass at the front but you can just see them. This is usually when they are close to dropping them. They are extremely tiny when seen and are located just slightly lower than the pectoral fins but above the anus in a big mass. Sometimes they have a small bulge or lump on this point too.
The females tend to be quite twitchy at this point so we have been unable to get pictures of them although I have often thought of trying. It usually goes like this.... reach for camera, cheni disappears.
As has been said before the Male usually digs a spawning pit and the eggs are hidden in there although we have seen one of ours once dig her own pit and drop the eggs in it. They stick together in a mass of eggs.