Hi Gabrielle,
First of all, I want to say i'm so sorry that you're experiencing this! I hear that because of the negative, and i'm sure disheartening, results you're facing from starting the birth control pill this month, you'd like some support around understanding how ending your current birth control would affect your fertility relating to a past experience, as well as in now switching options. Let me know if i'm getting anything wrong.
In terms of the impact of ending your current birth control, you can safely go ahead and stop whenever without it resulting in pregnancy from that recent experience. The reason why the doctors, nurses, or clinicians who perscribed you the birth control typically make sure to tell you it's best to wait a week before engaging in sexual activity that you can rely on as more protected is because the hormones released from the pills take a few days to activate in your body. For this same reason, even if you were to engage in sexual activity today and stop tomorrow, it would not have any impact on the result of that activity. Hormones both take time to enter and exit the body.
Now onto the question of switching methods. I would first recommend checking out
Birth Control Bingo for a comprehensive guide to birth control options. If you want to talk through these options to find out what might be right for you, we are happy to help you support you in that. Alternatively, If you have a medical provider you feel comfortable speaking with about this, they can be a great person to talk through your options with, especially if you use clinics like the US's Planned Parenthood where clinicians are trained more specifically on sexual health topics.
There is such a wide variety of birth control methods, and some tend to work for some people more than others. Even though the pill is one of the most popular, certainly doesn't mean its the only one that works. If you would like to prevent further hormonal changes from a birth control method, there are also great non-hormonal options availble like the copper IUD! How does all this info feel?