Erectile Dysfunction and Premature ejaculation in a 19 year old?

I'm 19 years old, and I suffer from PE. Also somewhat erectile dysfunction. I am able to obtain a weak erection, hard enough for penatration. once inside I get a more firm erection but still not at full capability. Call it a weak erection. Once I enter the vagina in less than a minute or 2 I find myself on the verge of ejaculating. I get a nervous feeling everytime I lay down with my girlfriend. When we first started having sex and with previous partners I never suffered from PE. Now when we lay down I get nervous about sex which I believe makes it harder to get an erection and causes me to *** fast. My whole life I've always gotten a weak erection around women except for like 2 times. What should I do? I have an appointment with a urologist next week.