How to start the conversation ? How to get help?

Ive been struggling with depression and anxiety for fee yrs now, its getting worse again. I feel numb and suicidal. I want to get help but I dont really now how to start a conversation with the doctor. I feel extremely anxious talking about what im going through with anyone, I know that if I made an appointment I would start crying and my mind would go blank and I wouldnt know wat to say.
Ive been to that doctor when I was 16, I felt like she wasnt really listening to me and blamed my struggles on exam stress even tho it wasnt true. She did wanted to reffer me to a mental health nurse but my parents were with me, I chickened out and said i dont need it. It was last time I seen the doctor, I fear she'll ask me about the last time even tho it was nearly 2 yrs ago. I also fear she wont take me seriously cuz i cant explain my struggles properly when im anxious and im gonna be emotional. What should i do or say? Im so lost

If you find it hard to get the words out perhaps you could write a list of all the things your are struggling with before the appointment and then either read that aloud or pass it to the doctor to read for you. I have done this a lot because I really suck at saying what I need to say. It's important to get help and not struggle with this alone.

Being brave can be oh so hard to do.

Realize that obtaining information and encouraging a patient to open up is something a doctor deals with multiple times a day. Please take solace in the knowledge you aren't the first and only one to remain tight lipped, hesitant, or even embarrassed that he/she will have dealt with. They are trained to deal with patients in a calm manner that should encourage a patient to feel they are in a safe space. Know too, that these professionals should be good listeners. And, if they judge themselves to be unable to do so, they are in a position to refer you to someone who can.

If you do encounter one of those jerks out there, please don't let that prevent you from trying again.

Reaching out can be a scary step. I'm glad you are trying though.
As Halloweensky suggested, maybe wiring things down (either list or paragraph) would be helpful. I regularly do this, both with doctors I've known for years, and new ones.
Another option might be to tell them over the phone if you are more comfortable doing that. It can be as simple as telling them you want to see the doctor for mood concerns (or whatever name you want to give it).
Most doctors, at least here in the us, will ask about mental health stuff in their initial history questions. I've found that simply not being able to answer those questions gets the doctor to look up from their screen long enough for me to nod...
I hear you saying you are worried about the doctor following up on your last visit. It might be a good way to lead into a conversation about your mood. If she asks about the referral, you can tell her that you chickened out because your parents were there, but you'd like to revisit the idea now. I'm guessing she has seen more than one patient who was nervous about following through on mh referrals due to family presence... also, that was 2 years ago. A lot can change in 2 years... I'm guessing she won't be mad or frustrated that you "didn't listen" the first time around.

Good luck. I hope you can make the appointment and manage to talk to her. I also hope she's receptive, which it sounds like she might be since she offered up a referral before.