Fitness and health anxiety

So I have been struggling with my weight since I was 8 years old and I am 17 years old today, I'll be 18 in November. I have been trying to go to the gym and eat healthy but I just can't get myself to go, I can't be bothered, I'm lazy, I'm too tired, always some excuse. I am seeing a therapist and she says that I should go to the gym especially if I'm getting a lot of social anxiety because the more I go, the more I learn that it's less of a deal than it really is and it gets easier each time. My problem is that yes I am super anxious to go to the gym (when I go alone), but I'm also just lazy and never know what to do in the gym. I have wanted to start personal training but the thought scares me so much. I son't want to know my measurments, I am a picky eater and seek comfort in junk food and I am afraid of feeling miserable because I need to eat nasty healthy food. I also am afraid of the personal trainer to judge me or think I am a lost cause. I also need to ask my parents for the money because I am not working because of my anxiety and I want to join a group personal training class but I am scared to land in a group wih grownups twice my age, or being judged or something and I know that they're probably not going to judge me because they are only thinking about themselves but the thought just scares me so much and what if I'm the fattest and they see that there is a fat 17 year old in the group and just FUCK it scares me so much and I feel almost embarrased of asking my parents and telling them that I want to start personal training even though there is nothing to be embarassed about nad just UGH this is eating me alive! It's like there is a devil and and angel on my shoulders and they are fighting and the devil is winning and I am stuck and I don't know what to do and I feel frozen and I just want to cry because I want and need this so much because I am scared for my physical and mental health if I don't, but I am also just scared of starting and I need help breaking the barrier, like I don't want to talk to my therapist about this because I'm embarassed but I don't get why I feel embaressed and what it is that is making me feel embarassed youknow? Ugh I could write about this forever but I am talking in circles cos my brain is all over the place so sorry haha and thanks for reading through all this if you made it this far