You have an extra call to loadForm() (you're already injecting the form via the named form element).
The position is just a CSS thing.
It's a little off-topic in terms of using the native Marketo Form Pop-Up but if you're building with Bootstrap I find it's easier to include a modal (pop-up) that contains your form and then it's much easier to change the trigger (or have multiple triggers) that fire the modal with your form inside.
Here's a link to the Bootstrap modal information if you're curious about how that works and the different options you'd get out-of-the-box: https://getbootstrap.com/docs/4.3/components/modal/