I know that

I am practicing my Irish == Táim ag cleachtadh mo chuid Gaeilge

but would

I was practicing my Irish == Bhí mé ag cleachtadh mo chuid Gaeilge

Thanks in advance

yep, looks perfect. However if you wanted to use the habitual forms of the verb as in "I am practicing my Irish(habitually, regularly, usually)", "I used to practice my Irish" it would be

a=bím ag cleachtadh mo chuid Gaeilge
b= bhínn ag cleachtadh mo chuid Gaeilge

Thanks, particularly for the habitual forms.
But shouldn't that last one be Bhínn ME ag cleachtadh mo chuid Gaeilge??

No, it shouldn’t.
There are verb forms without following pronouns in Irish, bhínn is one of them.

All such forms (for the 1st person) in case of the verb bí:

Táim = I am (no "mé") or Tá mé
Bím = I do be. (no "mé")
Bhios = I was (no "mé") or Bhí mé
Bhínn = I used to be. (no "mé")
Bheinn = I would be (no "mé")
Dá mbeinn = If I were (no "mé)
Bead = I will be (no "mé") or Beidh mé

OK, but then how would you say:

He used to be == ??
We used to be == ??

bhíodh sé


bhímis, bhíodh muid

You can find all forms of the verb bí on Wiktionary.

In 3rd person you always need a pronoun (sé, sí, siad).
Bhíodh sé.
Verb forms with pronouns are called "analytic verb forms": tá sé, beidh sé, bheadh sé, bhíodh sé, etc.

But in 1st person plural (= we) you had to use a synthetic verb form (i.e. verb and person combined in a single word) in Standard Irish until recently.
Bhímis = We used to be
In newer versions of Standard Irish you have the choice to use either bhímis or the analytic bheadh muid. Both forms* you will find in different dialects,

*) and variations like bhímist

Thanks for all the info