I second that it will get better with time. I absolutely hated high school. Just walking down the hallways was torture sometimes. I used to avoid the cafeteria and busy places too. I hid in the hallway and ate by myself and would sometimes even sit in for noon detentions when I didn't have one, just because I knew there was a teacher there to supervise, should anyone say anything to me. The fear paralysed me and I would often panic. So, I can empathize with you. I was in the same situation about five years back. However, my confidence has increased (though, just slightly) and I feel more comfortable talking to most people. I would say that things have definitely improved and I'm sure that they will improve for you too.
If I were to offer you any advice, I would suggest not to think too much about your future. Who you are right now and your current struggles do not dictate who you will be or what your struggles will be in the future. Don't give those struggles and worries that power over your life. I don't see anything wrong with dreaming about the future and making goals to aim for, though worries and judgments on yourself do nothing to improve your current situation or your future.
Right now, your worries are interfering with your health. They are dictating whether you eat or not and therefore you have given them a lot of power. When something interferes with your life like that, it is often a bigger problem than you may realize. You may want to talk to a trusted friend or find a counsellor to work through this with. I know that when I don't eat, I get more tense, irritable and anxious, so if you're anything like me, skipping lunch is not helping you at all.
Don't worry about struggling to get a job if you don't need to find one immediately or are not currently looking for one. I'm sure you have enough worries to deal with in the present time. And you do not need to work in a place that requires a ton of interaction. Just remember that people do mature. I have struggled with this myself and often avoid social situations, just because my experiences during my school years traumatized me. I sometimes avoid social interaction because I feel like people are going to behave the same way that my peers did in high school. Don't become like that.
The people you encounter in the workplace will not all be like your high school peers. They will not be as immature, self-centred and judgmental. When you get into the workforce, it's business mentality and no one really cares about petty things.
What you can do right now is try to practice talking to people. As Checkmate and 3pnt1415926535897932384 said before me, you will often think that others' reactions will be worse than they will actually be. You may think that people hate you or think you're weird, when in fact they may not and most likely do not actually think that. You'd be surprised how many people notice you and/or admire you.
If you talk to someone and the interaction goes badly, don't automatically think it's your fault. Some people are just jerks and what they say and how they treat you does not say anything about who you actually are as a person.
Start small. Don't try to talk to a ton of people at once if it makes you panic and feel self-conscious. Start with little interactions and the more you practice and talk with other people, the easier it will get. But don't expect to become super extroverted overnight. Also, hang around people who "get" you. Don't hang around (spend large amounts of time with) people who are negative and critical of you. If you don't have anyone like that in your life, try to find some good, supportive friends. There's no point in having friends if you can't be yourself around them.