Have you tried to get a credit line increase on your Macy's card?
In particular, what cards did you apply for? How many inquiries do you have on your accounts now?
What income amount are you putting down on your applications?
In any case, I wish you good luck with your schooling and volunteer opportunity. Be patient and don't lose sight of your goals, and things WILL improve, I promise 
There is work to be done here.
First work on Macy's try to get that CLI, use, PIF, repeat for leat two months and call them.
Join a Credit Union and get a secured card with them, if necessary change Direct Deposit with them.
See if you can get those lates removed, if not then wait until they fall off in two years.
If you are patient with your strategy it will payoff much better when you try again.
My advice is not apply blindly but to choose carefully and work smartly with what you can get.
Whatever card you get approved, no matter the limit, you work on increasing those limits.
Do not add more cards unless is absolutely necessary. It will kill AAOA and keep your score low.
This has worked for me but it took patience, self control and time.
Good Luck
Starting Score: 660 - 2010
Try a local CU as someone suggested: you have a good story, they may well listen to it actually and be willing to help you.
The second one I would suggest is probably a secured card from Capital One: $99 gets you a $300 limit to start (or if you can afford more cash wise, you can get a larger limit), it's a Visa which does acceptably internationally for your volunteer activity, and there's no foreign exchange fee either. It's going to be hard for you to do better where you're at now.
They have a prequalification page, you may be able to qualify for an unsecured card there as well though their secured product has a solid degree of flexibility if you can afford more than the minimum.
In any event, if the Macy's card is still reporting that's enough from a FICO perspective with an additional credit card to put you in pretty good shape though likely if you can arrange two cards without depleting your financial reserves that would likely be better. Sounds like you've disclosed pretty much everything, what's holding you back is income and a lack of recent history, the Macy's card may well even be flagged as Inactive on your credit report, have you checked it / charged anything to it recently?
So pickup a card or two, make sure your Macy's account is in good standing and if it's not, fix it, wait for a year, and then be qualified for the real versions of the student cards you were applying for. It's not instant, but it's a decent starter plan I think for your situation.
Oh one which might be better depending where you go, look into SDFCU (state department federal credit union): there's no credit check for membership, and no credit check for their Secured card either, and honestly it's one of the top 5 secured products available in my opinion: even has an EMV Chip/PIN combo which is unheard of for a secured card anywhere else, in addition to not having a foreign transaction fee, and that's as good as it gets for international use these days depending where you're headed.
Also under more advanced building topics, if you have some positive cash flow I'd suggest getting a secured installment loan too: some places will even lend you the money like this one as an example of what you're looking for: https://www.dcu.org/loans/credit-builder.html