I would recommend, humbly, two things for you.
First is this wonderful article on scrupulosity: catholicpamphlets.net/pamphlets/Are%20You%20Scrupulous.pdf
It makes a good case for many things, including the principle that, if you have to ask if your actions were mortally sinful, then they probably weren’t.
(Edit: By the way I’m in no way intending in to imply that your question is scrupulous. On the contrary, I simply interpret it is as a new Catholic asking questions to help form their conscience in accordance with what the Church teaches. BUT … that article is simply wonderful and I think you’ll learn a lot from it.)
Secondly is this incredibly long and detailed examination of conscience: materdeiparish.com/wp-content/uploads/2015/06/Examination-of-Conscience-for-Adults.pdf
That examination should not lead you to be intimated, but rather is an excellent resource to help form your conscience insofar as knowing what type of sin is venial and which is mortal.
Indeed, on the section on meekness in that examination, you’ll read the following:
Have I given in to sudden spurts of anger by harsh words, by calling names, by abusive language?
You’ll also note that this is listed as being a venial sin.
But a mortally sinful version of anger might look something like this:
*Have I deliberately permitted myself to become so violently angry that it destroyed my reason for a time and made me incapable of acting like a human being?
Very few examinations are broken up by degrees of seriousness, as this one is, and I think it is a tremendous help in analyzing one’s actions.