Yep, as Tari says, it seems to be pretty typical for a trip to the dietician!Was definitely the case with us.
In regards to leafy greens/green veg as a source of calcium for LOs, they would need to consume such vast quantities of it to get the calcium needed that you can't really count on that as a major calcium source. For instance 1 cup (250ml) of raw vegetables will give you anywhere from 25-55 mg of calcium on average. High sources of calcium for vegetables is really in thins like collards and turnip greens, spinach, etc - where a cup of these, cooked (so probably about 3-4 cups uncooked) will give you 150-200 mg of calcium. This would be assuming that all of the calcium from these vegetables is absorbed, and really, it's not absorbed anywhere near as well as it would need to be. Not sure how old your LO is but toddlers from age 1-3 need about 500mg of calcium per day. So your LO would need to eat at least 10 cups of vegetables or about 3 cups of cooked spinach to get the calcium requirements that can be had from 12 ounces of milk...this is why they really push the milk/soy milk on you as a calcium source.
For fish, the best source is really the bones, not the fish itself, and the fish sources that rate high in calcium are tinned sardines and salmon, both with bones in - sardines are better but salmon is a good source as well. Other fish is again just not going to cut it like milk or soy milk will.
Sorry to hear the appt was a bust, I do remember feeling that way when we left our appointment as well.
You mentioned you are looking for other sources for calcium, is it because he does not like the taste of the soy milk? Alpro does soy milk in loads of flavours, not sure if all of them are available in the UK but here we can get it in plain, chocolate, vanilla, banana, strawberry or wildfruit. DS loves them and I switch it up now and again when he is getting bored. They also do nice yogurts and puddings. Oatmeal is a good source of calcium, as long as you get a fortified one, and if you make it with soy milk then it can provide a large chunk of the day's calcium requirements if he eats a good sized bowl of it.
HTH!