I pray, but I secretly worry my salah is not accepted because of my other faults and sins. How can I stand before Allah when I feel so unworthy of Him?

That worry is not evidence against your salah. The man who never wonders whether his prayer is accepted is not the one asking this question; you are asking because you care, and that is a heart still awake. So let us look at what Allah Himself says to the one who feels he has fallen short.

Notice who He is addressing. Not the flawless.

“Say: O My servants who have wronged their own souls, do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.”

Qur’an, Az-Zumar 39:53 · meaning

He still calls you “My servant” even while naming the wrong, and He forbids one thing only: despair. Notice also on what basis the prayer was given to you. Not your worthiness, but His remembrance.

“Indeed, I am Allah. There is no god but Me, so worship Me and establish the prayer for My remembrance.”

Qur’an, Ta-Ha 20:14 · meaning

So the prayer mat is not a stage where only the perfect may stand. It is a washing place. The door opened because you knocked, not because your hands were already clean. And the Prophet, peace be upon him, told us that these same daily prayers keep clearing away the dust that gathers between them.

“The five daily prayers, Friday to Friday, and Ramadan to Ramadan, are an expiation for whatever is between them, so long as the major sins are avoided.”

The Prophet (peace be upon him), Sahih Muslim (233a) · meaning

So do not measure your standing by how worthy you feel. Feeling unworthy is not a verdict against you; it is what a soft heart feels. Come as you are. The One who invited you knew your state when the invitation was sent.

One small step: Before your next salah, pause for one breath and say quietly in your heart, “I have come because You called me,” and then begin, trusting the invitation more than your own worthiness.