There isn't too much you can do for penis size, though there are lots of devices men try to enlarge it. Most are not worth it and can cause damage (some really serious damage) to your penis.
Most women don't care nearly as much about penis size as men do, and if your partners are men, some prefer men on the smaller size.
As to ejaculating quickly, there are sprays you can use that help numb the area, which in turn delay ejaculation, or you can masturbate prior to sex, use condoms (if condoms prolong things for you) - there's a lot of things you can do. Here are some tips - https://www.mayoclinic.org/diseases-conditions/premature-ejaculation/diagnosis-treatment/drc-20354905
Don't forget foreplay. If you spend a lot of time on that beforehand, a lot of people are fully satisfied with that.
"She even sometimes act like she is enjoying the process."
I'm sure she is. Do you have an open communication with her about sex? Do you talk about what each of you like and don't like? She may have meant something entirely different from her "don't feel like getting penetrated" comment than you think she meant, and it's important to talk about that.
Have you ever heard of edging? Here's an article about it - https://www.vice.com/en_nz/article/43eb8d/edging-and-other-techniques-to-make-sex-last-longer There are hundreds of more graphic articles out there. I'll let you search for those yourself. :)
Really - Communicate. Talk. (This can also be really fun.) Foreplay. (Also really fun.) Relax. Enjoy.
Diet may help, avoiding unhealthy foods and staying healthy and on a balanced diet would help, dont have too much red meat as that will not help you. Dont take too many cold showers either, stick to warmer ones