I do not see all my topics here

Here’s one from 2013: discussions.apple.com/thread/5407704

Here’s one from 2014: discussions.apple.com/thread/6496087

Here’s one from 2019: discussions.apple.com/thread/250297062

Found in the first two pages of Google’s search results with the suggested keywords.

They’ve added dates in the short description on the (unsorted) search results page, so that makes it a bit easier, if you (want to) know the (approximate) age of the thread.

Three months is about normal. We are other end users and cannot give you an official reason why that specific limitation is in place.

Old posts are not removed; they are simply no longer indexed for finding with the forums software's internal search function.

However, you can use a search engine with a site-delimited search string to quickly find very old posts here. For your username, you search with this string:

site:discussions.apple.com "Bomiboll"

👉🏻 NOTE there is no space between the colon after "site" and the d in "discussions.

You can further limit a search by adding other parameters in quotes. Example:

site:discussions.apple.com "Bomiboll" "2023"

to limit the search to one year, or

site:discussions.apple.com "Bomiboll" "reset SMC"

to limit to a subject.