Some poor advice on this thread. Absolutely do not eat only 500kcals/day. It's FAR too few. That's how people end up developing disordered eating. Genuinely, I work in mental health services, and a lot of people with anorexia aspire to 500kcals a day. Rapid weight loss is not good for you. Healthy weight loss is only 1-2 lbs a week. You will lose more initially if you're bigger as your water weight comes off.
I'm 5"1 and lead a sedentary life and my maintenance kcals (e.g. how much you yourself burn in a day doing nothing) is 1500. I loose at about 1200. For most people, this is too few, unless you're tiny like me and don't do any exercise. I personally don't eat breakfast because I'd rather have a larger evening meal. For most people though, a light breakfast is part of a normal day and most research backs up that breakfast is good for you and keeps you fuller throughout the day.
Carbs are also absolutely not bad for you. It's a modern myth. You need carbs for energy as part of a healthy diet. There are plenty of very healthy carbs, like wholegrain rice, sweet potato, etc. Diets like keto work because proteins/veggies generally have less calories so people naturally eat fewer kcals. Healthy fats are also great for you, like a handful of nuts, a bit of cheese, etc.
5 fruit/veg a day is a good target, but in reality it's better to have more like 7-10. It's easier to get them in than you think by blending onions/carrots into pasta sauce, throwing an extra handful of greens into whatever you're eating.
I personally eat tons, but I volume eat veggies! You're right that portions of pasta etc are very large now, but 50g of pasta will feel like nothing unless you bulk it out. If you cut carbs portions a little, and bulk it with things like a handful of nuts, veggies, pulses, etc, it will be less kcals but will be as filling.
Lots of wholefoods is generally the way to go.
And honestly, I wouldn't worry what you're eating in a restaurant. Pleas go out and enjoy your meal. Life is too short to be calorie counting the massive steak and chips you had out for a birthday. A giant portion every now and then won't kill you, not will a bit of chocolate, some processed foods etc.
Just do you. Eat a generally healthy diet, and don't worry if you have a fish and chip night on a Friday. If two larger meals a day or lots of smaller ones work better for you, do it.
But please, don't think eating 500kcals a day is normal because it really isn't.