Your speech must be cot-caught merged. This is a perfect example of the kind of systematic phonemic merger I alluded to earlier. I keep these lexical sets distinct, but I did grow up speaking a dialect with the cord-card merger. (But not horse-hoarse merger; can anyone tell me which one that is?)

Do you know if the cot-caught merger is used in Standard American TV English? Because, I always hear a full merger in the speech of actors, singers, news anchors, and the like, but according to Wikipedia, only ~40% of Americans have the merger. I was wondering if they actually have the merger or it was simply me perceiving all of the vowels as /ɑ/. **I had trouble writing this coherently, sorry.

I can't be of any help to your dialect question; I've never heard someone with a cord-card merger nor someone without a horse-hoarse merger. Haha.

Most of those Americans are located in the West (including LA), though the merger is now spreading into the Midwest. Still, I don't think it's conquered broadcast English just yet. I don't generally watch broadcast news, but it was clearly absent from the older generation of news anchors (such as Jennings, Lehrer, Brokaw, etc.). A lot of television actors come from Chicago and New York, where the merger is absent, and preserve the distinction when speaking in their native accents.

I’ve got a question regarding the American pronunciation, I know maybe it’s not the section of the forum where it should be asked, but since you are already talking about American English, I’d like to take the opportunity to ask about it.

Well, it’s about something I’ve always heard from my teachers, they always say one feature of American English is the merger of t’s and d’s between vowels and that they are pronounced like d’s. And, even though I’m aware of this, I’ve made a mistake in my English class because, in my opinion, they are not pronounced exactly as a normal "d". I mean, my mistake was to single out the pronunciation of the "d" in the word “reading” as a characteristic of American English, and the teacher said it was pronounced as in any other dialect and that the typical feature is the "t" softened to "d", but the point is that I do think the “d” in “reading” or the “t” in “writing” are equal, but not pronounced exactly as the “d” in “day”. In fact, we Spaniards hear it quite like a Spanish soft “r”, but it could be just a confusion we have. I don't know if I was too clear...
What do you think?

You're talking about a process called intervocalic alveolar flapping, which though also present in other varieties is particularly widespread and prominent in American English. Indeed, the resulting sound is identical to Spanish ere, but most English-speakers don't realise this and perceive it as "d".

The Wikipedia article I linked to gives a pretty comprehensive overview of the phenomenon but one interesting detail it omits is that alveolar flaps are optionally deleted in informal speech. That is, reading may come out not as ['ɹi:ɾɪŋ] but as ['ɹi:.ɪŋ]. (In rapid speech, vowels may coalesce, but my general perception is that they're kept distinct.)

Thank you very much You really made me feel better, I thought I was deaf or had too much imagination...^^