The speaker is saying that a smile can hide how they really feel. Each time the line "Just because I smile" comes back, it works like a warning: don't take this expression at face value. They tell people not to assume they're okay, not to think they're truly happy, and not to push them to be even happier. The smile is more of a mask than a mood, and the speaker says it doesn't mean life is perfect or that they feel like themselves.
The tone shifts near the end. The speaker stops only pushing back and begins to ask for something: keep checking in, and "help me get through this stage." The line about wishing life would get better shows how tired and hopeful they are at once. The mood is raw, honest, and a little vulnerable. The plain wording and the typos make it feel like a real, unpolished message from someone who wants to be seen.