I need relationship advice

Hi my girlfriend just confessed to me on first of August, and I'm surprised because we just became friends 3 months ago, my friends are very surprised aswell since she is VERY VERY lesbian, like very lesbian, I managed to turn her straight.

I have a rough past with my ex girlfriend, let's just say she spread rumors about sexual stuff and I'm afraid that she'll do the same, I have bipolar disorder aswell so she might get tired of my constant moodswings.

I am planning to give her a gift tonight, some food and letters.

How will I know that this relationship will last unlike my last relationship with my ex that lasted half a year but was very toxic