I do understand the feeling of being hung up on looks, I loathe the way I look. I too have bags and dark circles around my eyes (hereditary and stress related), and I have bad teeth, acne, large pores, a wide-ish nose... and I've thought about getting surgery a number of times. I always see my mother or my father when I look at myself, I want to look nothing like my father because he is scum to me, and not a very nice looking person. My mother constantly complains about how she looks, she doesn't even like her photo taken and whinges when she sees pictures of herself, so the fact I do resemble her does not help my esteem at all.
I wear a lot of makeup now, I never used to wear it at all, and it made me feel a little better until someone told me I looked better without it, and since I feel like a complete ugmo with no makeup on as it is, you can imagine how that made me feel.
I don't think I've ever had anyone ever tell me I was ugly, I usually get quite the opposite, but it doesn't help me feel better at all. I hate compliments in fact. What I see and what others see seeem to be 2 completely different things.

When it comes to acne, I have found birth control has help a lot, since it is hormone related. Is that something you've tried? Hormonal acne tends to show up mostly around the jawline, sides of the neck and lower cheeks. Plus picking at it too will make it worse, as it takes longer to heal. I learned that the hard way. My acne sometimes would get so bad that it would be hard to sleep on that side of my face, and it would almost look parts of my face were swollen. I still have a little bit of acne, but nothing like before. It takes a few months to work too.

I do enjoy makeup, and I spend forever on pinterest learning different tricks, and I actually enjoy putting makeup on every day.
It sounds like you have very sensitive skin, and as some makeups make people break out because of specific ingredients in them, you could always research different types of makeup for sensitive skin, and what ingredients can aggrivate it. Or is it because the sunscreen you have you wear underneath is is so heavy that it's contributing to it?

You said that you burn really easily and that you have you put sunscreen on, have you tried foundations that have sunscreen in them? I know you are allergic to some things and you say titanium dioxide doesn't work for you, but perhaps one in a foundation might as it is mixed in with a product (I could be totally wrong on that but hey). Otherwise if you can find a foundation/bb cream that has something you can use in it that might help a little. Just remember when it comes to photos that a lot of products used for sunscreen can make you appear white when flash is used.
If you really just cannot wear foundation at all, is there a tinted moisturiser or something you could use instead?

As for bags and dark circles, there is no makeup trick that completely gets rid of it, but there are ways you can reduce the appearance of it. I don't know what you've attempted before, but it's not just the products you try but how you apply them. When it comes to colour correcting, you want to use a base that is the opposite of the colour you're trying to hide. So if you're trying to hide something with redness, use something with a green base. If you're trying to cover something purple, use something yellow based.
Then when it comes to covering eye bags, you want to be careful how you apply your makeup as it can sometimes bring attention it rather than hide it. some people just try to conceal the under eye area only, when it should be applied like this-


I do that first as a base, to even out the colour, then I add a darker shade to the puffy area, and put a lighter shade in the crease. Darker colours add depth, whereas lighter colours highlight and bring forward, so adding depth to something that sticks out, and bringing forward something that sinks in can create the illusion of flattening out the bag of your eyes. Just make sure to blend it well, don't use shades more than say 2 shades lighter or darker than your usual shade, and practice a few times before you walk out the door.

When it comes to haing a wider jaw line, again darker and lighter shades can help. Contouring add definition to your face shape, and adding a darker shape around your jawline can make it appear thinner. Marilyn Monroe used to to this, and highlight the eye area, to make her face appear more heart shaped instead of round. She also used to use winged eyelashes and shadow to make her eyes look wider, which may help if you have smaller eyes. There are plenty of makeup tips out there for people wanting to make their eyes appear larger, and how to do makeup for hooded eyes.

If you can watch youtube, look up goss makeup artist. He's got a lot of tips on how to do makeup for a lot of the things you've mentioned, plus his personality is really great and tries to explain how to 'fix' different features without making it seem as though you're ugly to have the features you feel you might need to fix.

I probably haven't helped in the slightest, but hopefully I've given you something that may lead to you finding a trick that will make you feel happier about yourself.