feijoa pineapple guava

[MameyDisco]

Just to clarify and no hard feelings, both Feijoa / Pineapple guava Acca sellowiana & Cattley / Strawberry guava Psidium cattleyanum are indeed in the same plant family, Myrtaceae. They're in different genera. Something to note, for their relation and understanding of culture for individual species.

If they are only a couple of years old, that is probably not old enough for them to be producing.  Give them time. Pineapple guava (Feijoa) is not in the same family as strawberry guava.  They are not actually guavas at all, so you shouldn't compare them to productivity of the strawberry guavas.