Don't worry. Everything can be solve.
It's good you notice your body changes early as early diagnosis will always have more solutions that you can choose from and also more time for you to decide.
Don't worry about how the society view you. Most importantly is how you look at yourself. Get a pregnancy test done, no one has to know about this, you just go to the pharmacy, buy and use the test andden dispose it. If it's negative then stop stressing yourself over this.

Also, you're not even 18, high chance your hormones have not been completely stable yet, considering you are still in your teens.
It's better to get a gynae (I assume you don't have one right now). And go to her for advice and consultation. There are many other things that can trigger hormone imbalance and you may be able to pinpoint the reason as to why your period is getting lighter each month.

And always use protection if you don't plan on getting pregnant.