OK you've only had three lessons so it's going to be pretty difficult and stressful at the start, but you'll get nowhere by giving up.
If it helps, I have coordination issues too (not something I'm making up, I was assessed as a child), and initailly I had a pretty impatient and short-tempered instructor who would start getting angry when I stalled the car or didn't use the clutch correctly, and this was only around the 5th lesson, so I convinced myself I couldn't drive manual and got an automatic instructor. Although obviously I didn't have to worry about clutch or gears I didn't really find that much of a change in my other driving ability, and gave up for a while as I live in London and don't really need a car anyway.
Recently I wanted to take up driving again and found an instructor who was much more patient, this is when I realised that practice makes perfect, and you have to expect that you're going to stall the car and not panic when you do. Other drivers, especially if you live in urban areas, can be aggressive and think it's smart to honk their horn and look pissed off in the rear mirror, you just have to ignore them and carry on at your own pace. It's also perfectly noprmal to find it difficult to be aware of other cars on the road and hazards when you start driving. This is the whole reason people have to learn how to drive and they have to take a test before they can do it on their own. Your parents might make it look easy but that's because they've presumably been driving for years and have got used to seeing out of a windscreen and judging the speed of other cars on the road, etc.
You'll get there eventually, there is no point in giving up. If you're having issues with clutch control and changing gears you should try and practice it as much as possible, remember that you can get insured on your parent's car and they can supervise you (insurance costs about £75 a month for learner drivers and the only other thing you need are L plates and possibly an extra rear-view mirror), assuming their car is a manual. I know it can be hard at the start but I'd strongly suggest learning in a manual, in the UK it's the norm to drive a manual and insurance and maintenance costs are often cheaper than automatics. And regarding spatial awareness you just have to carry on practicing, your instructor will stop you if you get into a dangerous situation and you usually aren't driving very fast anyway.
In terms of your medical condition, I understand that you can drive even if you can only see out of one eye, so if your sight is deteriorated in only one eye then that should be fine. But if you're worried check with your opthalmatologist.
I hope I helped at least a bit!