I don't think you need to be depressed about your current scenario. If you've met all the other requirements, establishing that you were here on June 15, 2012 is probably the "easiest" of the criteria to satisfy and my colleagues have already pointed out excellent ways to establish that.
I would still urge you to partake in a free consultation with a lawyer to ensure that you haven't overlooked any remaining criteria. Best of luck,
Sanjay Paul, Esq.
This is not legal advice. No attorney client relationship exists between us.
The documents you may use to prove that you were physically present in the US on that date are not limited to those mentioned in the DHS guidance. Look for any documentation to show your physical presence on that date like mails, phone logs, photos, receipts, etc. If you can't find anything that is exactly dated June 15, 2012, you may try using documentation dated before that date and after that date, and present your passport showing that you never left the country at anytime during that period. The USCIS will look at the totality of your evidence in determining whether you satisfy this particular requirement.
Hope this helps.
I definitely encourage you to consult with an experienced immigration attorney before applying just to make sure that there are no outlying factors that could have any negative impact on you in your particular case before applying. However, proving that you were here on June 15, 2012 should be the easiest factor to prove, so don't stress out just yet. Where were you on vacation--surely you have proof of where you were? Pictures with the date on them, receipts, your bank statement showing you used your debit card in the US on that date, a phone log showing you made phone calls in the US on that date, etc. Good luck!
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