I agree with the advice above - wait to see how your AS grades go, only do three A2s, and at least try applying in the UK this year if only to become more familiar with the application process - there is still a chance of getting an offer.
Try and get AAA predictions at A2 - if you get ABBB at AS and your Bs are quite close to As your teachers may be more flexible. Having lower than AAA will disadvantage your application somewhat...
Also, I would recommend trying to get more work experience - from what I've heard most medical students have done a lot more. It doesn't have to be directly in a hospital setting working with patients - you can also do voluntary caring work (e.g. in an old people's home/ nursery/ with disabled kids at an activity centre/ whatever) for example. They are looking for someone who has a passion for helping other people as well as the grades etc. If you end up taking a gap year, don't worry - this is the perfect opportunity to get some more work experience, particularly as you will be able to volunteer during the day during term time, when A level students will still be in school. You could get in touch with local charities, hospitals, care homes, nurseries, children's clubs, etc. and offer to help out. Some people go abroad to do medical placements - however you tend to have to pay a lot for these and the companies offering them are usually profit-making and not all that interested in helping the local community.
Studying abroad will probably be very expensive - and it would be better financially if you were able to get into medical school in the UK, even if you need to take a gap year.
You mentioned a need to support your parents financially - although they are your family it is not your duty to do so, and your siblings also have equal responsibility. Even if they don't go to university, they should still be working and attempting to progress within their career. It should not rest on you to support your family - you also need to think about what is best for you personally. You parents should have some kind of pension fund (or if they are UK citizens they should be able to get some state support - although I'm not sure of all the rules around this, they may need to have paid national insurance or something. No idea. Look it up if you want to know) and savings to rely on.
If you were solely motivated to financially support your parents you would be studying something like economics/ engineering etc. - a nice short 3 year degree with high graduate salaries. Studying medicine takes over twice as long, and even after graduation you still need additional training to read higher paid roles. Think carefully about why you want to study medicine - are you motivated to support other people etc. or do you just want a almost guaranteed, well-respected job with a high salary?