Within the forums, you may need to use the Filter to set the view to "Authored" to make sure it lists all threads you have initiated. I get these:

The default viw is "Following" and may miss some posts. Even so, the list can be slow in updating or miss a post or two.
Threads older than about 3 months seem unavailable through the forums software. I have an idea why but speculation is not allowed here. This is an old bug of which the moderators are aware.
To find older posts, I use a site-delimited web search in a regular search engine. For you, the search string would be:
"AleGallo93" site:discusions.apple.com
Note the quotes, and that there is no space between "site:" and "discussions"
...but shouldn't I be able to find all my posts/subscripitons directly (in an easy way) from my account?
It would seem so, but responders here are not Apple employees or agents but other end users like you. We can only show what works for us. I can send a note to the mods asking them to review your comments, but cannot guarantee they will respond.