dinkymints I'm a longtime vegetarian and in the last few years I've avoided preordering my (economy) meal because inevitably there would be no protein. Most of the time you'd get a salad to start, rice and veg as a main and then a fruit salad for dessert. Many times I've left the plane starving. As you said, I suspect the VLML is often also a VGML, AVML, GFML... etc.
When I travel in Club, I haven't ever ordered a meal in advance. I do suspect that, when travelling from outside Europe at least, whenever they say "parmesan" they actually mean a hard cheese that's most likely made with microbial rennet. I generally avoid desserts as I'm not much of a sweet tooth. It's worth asking the cabin crew because their allergy info might also say if the dish has gelatin since many avoid it for religious reasons.
A friendly word with cabin crew right when you first get the menu to say that you need a vegetarian meal and I'm sure they'd oblige. I've done it before and always had one kept for me. That said, I don't remember being on any flights where it ran out!