Hi Kira,
(capital letters are for emphasis, I'm not shouting; and sorry for the driving analogy but is seems to fit for some reason)
As a relative beginner I have gone through the same processes as you and I have put some things down here that have helped me.
From what you have said it's like you are trying to take your driving test without lessons, in a Porsche (and a left-hand drive one at that) and are upset because it stalls/crashes/exhausts you before you have learnt how to drive it properly; and all the driving instructions are in Russian in any case. When you crash for the 15th time is it because you are rubbish? No, it's because you are trying to do the impossible too quickly.
So, by all means give up. Give up trying to do something that is impossible...
... give up trying to take photos like the professionals - because you (like me) are nowhere near professional level;
give up being depressed about learning a new skill - it's complicated so it is bound to be difficult;
give up expecting to know it all immediately (or even quickly) - not going to happen;
give up comparing your pictures to those taken by people who actually know what they are doing - only look at other pictures to learn what you can from them and to be inspired by them;
give up trying really complicated pictures - go back to basics with solid, static, high contrast objects (wine bottles, ornaments, glasses, books on shelves etc) and get comfortable with the differences made by shutter speed, av, composing, distance from objects, etc. etc. and learn your camera and a bit of processing; this will show you what you can and can't achieve and what you really need to look out for when you are out in the real world with your camera;
give up being hard on yourself when the inevitable happens - you take a picture that doesn't come out the way you want;
As a beginner, take each picture in relation to the last one - is it better exposed, better focused, better composed? When you have got all the bits right for that one notice WHY it is right - then move on to another. If you can't get it 'right' then accept that you haven't learnt the necessary skills yet and continue to practice just the skill (not the picture) in a less complicated way. Can't get the shallow dof on a flower - try the computer keyboard/books on a shelf, focus/recompose/AI/Servo etc. there and see/learn the differences. Then you WILL know what is going wrong when you try the more complicated shots and you WILL know what people mean when they give you feedback.
But most of all, on a personal level, do yourself a favour and give up doing jobs for people - if they want to lend you their child or their pink cab so that you can practice that's their look out. I think you could give up trying to take specific pictures and concentrate on learning how to take pictures in general. As a beginner myself, I can say that realistically you don't have a snowball's chance in hell of reliably getting the type of picture you want - so why set yourself up to fail like that? Why set yourself up to the stress of even aiming for that?
At the moment you are asking "what am I doing wrong?". When you get to the point of knowing what you are doing wrong/what is going wrong and still can't correct it despite at least a year of practice ONLY THEN will it be time to think "can I do this?".
Get on with learning the art and craft of photography and enjoying being creative. When a picture does come out that your SKILL and KNOWLEDGE has achieved enjoy it and feel proud ......... and if you can't do that then, yes, do give up.