Decided to try to finally have a baby by myself

So I am turning 35 this year and I still haven't had any luck finding a man, so I been thinking about other ways to having a baby (finding a donor from a sperm bank) now the hard part is I do really want to have twins, I am on a low dose birth control but also have been taking prenatal vitamins, I know I have to stop the birth control pills but dont know how long I would have to wait.

Would ivf guarantee twins? Or would I have a higher chance getting fertility treatments that can cause multiple eggs to develop aswell? I still dont know which route to take (having an egg fertilized out of my body or internal insemination at a clinic)