How do you handle premature ejaculation during sex without masturbation?

I tend to naturally be pretty quick in bed. However, through consistent masturbation and edging my stamina greatly increases.

My new girlfriend does not want me to masturbate while we are together, which I am okay with. The purpose of this is to maintain my sexual energy for when we are together. We currently only do oral sex, during which I come quickly but am able to please her well, but I think that once we do start having sex I will not be able to please her effectively lasting only a short time.

What are ways that you can work on sexual stamina without regular masturbation?