Firstly, we should consider that " suddenly social media is filled with transgender teens" is an anecdotal statement. Not that there's a problem with it, I guess my point is that it is subjective. They are still less than 1.5 percent of the population whether you perceive that you have seen a lot or not... I could say your experience is contrary to my experience -- I haven't seen very many transgender people on social media at all, and rarely see other transgender people unless I specifically seek it out. See this is my experience, which is valid, and that was your experience, also valid -- so the point becomes moot -- there's also some subjectivity here as you might be more likely to notice a transgender person.

If the entire social ecosystem tried to enforce that I was a man, I got told everyday I was a boy, was bought boy things and boy clothes, how is it that I turned out to be a woman?
How is it that an entire social system, as well as prejudice people, are incapable of changing someone's gender -- as it didn't for me -- but seeing a transgender person is going to change their gender?
You're viewing gender as a very mutable thing, but it is tied to your early development and your sex. And yes, your sex -- which is not binary but fluid as people have different sexual characteristics regardless of a single chromosome difference or genital configuration. I myself am intersex, which just goes to show that there is not A and B, there is A-B. Humans break things down into categories when they are continuous; this is in fact the form in which categorical values exist; as labels of continuous features. Sex is an example, we work well to have 2 sex categories socially because there is no possible way we could label all of the " numbers" between male and female, which are blanketed in intersex. In reality, X and Y are significant -- they determine the category of your sex. However, there are still sexual variations within these categories; some men release more testosterone, some women have bigger breasts.
The reason why I bring this up is this...

"""
The available research indicates that the brain structure of androphilic trans women with early-onset gender dysphoria is closer to that of cisgender women than that of cisgender men.
"""
From https://en.m.wikipedia.org/wiki/Causes_of_gender_incongruence#:~:text=The%20available%20research%20indicates%20that,in%20non%2Ddimorphic%20brain%20areas.

This is a fundamental characteristic of sex; forcing it to change does not work, just as it did not work for me.
As I addressed in the article; there are other countries with more accepting societies which have more transgender people. The population percentage tends to even out around 3-4 percent.

How could we possibly know how many people are transgender when it is a closeted trans person's biggest secret?

Take a look at the euro statistics here is a histogram that shows which countries are the most accepting of transgender people based on a survey of questions about transgender civil rights:
https://www.google.com/search?client=ms-android-att-us-revc&sxsrf=AJOqlzUt5mwijUuPewhI6RTljpxsraRWXA:1679519423163&q=trans+people+by+country&tbm=isch&sa=X&ved=2ahUKEwiWjvG0ufD9AhUWEVkFHd_UDL4Q0pQJegQIChAB&biw=412&bih=769&dpr=3.5#imgrc=O_JerzpMminEOM&lnspr=W10=

Then notice how those different values correlate to the overall population of transgender people:
https://worldpopulationreview.com/country-rankings/trans-population-by-country

You will be yourself so long as the opposition does not make you fearful to be yourself. Therefore, if you saw a transgender person but you yourself were a man, it is unlikely that you would suddenly become transgender.
I mean I've seen a lot of men in my day, still I'm not a man. And you probably see women everyday, does this make you want to become a woman? Then why would being a trans woman be any different? I don't know, just seems like an odd thing to think -- the mere nature of my existence is going to influence other people to become me? Then why is that not the case for everyone else?

I think my final response to this would be .... Okay..? So? Even if we were a social contagion or whatever (we aren't), who cares? Why are you upset that more people would be transgender? What's wrong with that? Why is that a big deal? It has no effect on me whatsoever, I mean aside from the fact that more trans people probably means I could get civil rights again.
It's kind of like being afraid of rap music because your children might start adopting black culture. So? What's wrong with black culture?

It doesn't matter if everyone on Earth is transgender or not, what matters is how we get to that point. It also doesn't matter if no one on earth is transgender, it matters how we get to that point. Now of course, everyone will never be transgender that is silly, but how are transgender people being " a social contagion," would you describe this as of the child's free will, or not? Is the child willingly submitting to wanting the change?
As opposed to the historical alternative, where we have forced men and women to behave a certain way and casted transgender people into insane asylums?

Nobody is forcing anyone to be transgender... In fact quite the opposite, the experience of being transgender is mostly listening to people try to tell you you are not transgender.