Naming convention for adduct ions
Your convention is generally correct; as more complicated adducts and ions are formed (clusters, adducts, neutral losses, etc) things start to become a free for all where the clearest terminology wins.

As of now, just go with (where A means adduct):

$$\ce{[M + nA]^{n+}}\text{ or }\ce{[M - nA]^{n-}}$$

Protonated molecules can be denoted as $\ce{[MH]+}$ (common) or $\ce{[M + H]+}$ (technical). The $\ce{[M + H]+}$ convention is more precise because if you write $\ce{[MH]-}$ for a deprotonated ion the interpretation becomes muddled (i.e is this a hydride adduct or is this a deprotonated ion?).

One important think to keep in mind that is Molecular Ions ($\ce{M^{+.}, M^{-.}}$) are not the same as $\ce{[M + H]+}$ or $\ce{[M - H]-}$ and that the terminology is not interchangable.


$\ce{M^{+.}}$ or $\ce{M^{-.}}$ retains the elemental composition of the ion and is ionized through the removal or addition of an electron.
$\ce{[M + H]+}$ and $\ce{[M - H]-}$ are protonated and deprotonated molecules, respectively. They are not 'pseudomolecular' ions as there are no such thing as pseudo ionized specties.