*important* forced to switch from adderall to ritalin temporarily because out of USA

Hello all...I will make things as brief as possible:

I am in a 3rd world country right now (Iran) visiting my fam. and I have decided to stay longer and have run out of my meds. They don't have adderall or amphetamine salts because of the amphetamine and I could not get my hands on it whatever I did (I even went to a special doctor and got a special prescription and went to the Red Cross but they never have it in stock).

I called my doctor and he called my gf and told her for the mean time, I could substitute my medication with ritalin.

Now, my prescribed dose of adderall was 60 mg/day but I have been taking about 30 mg/day since I have been here. I got Ritalin...but I will start taking it tomorrow as I just ran out of my adderall tonight.

What kind of differences should I notice and what should I do to make my body prepared? Is ritalin like adderall in the sense, when I take it I notice the immediate effects? Or unlike adderall, does it go in the blood stream long-term? I want to know how I should prepare for the effects of ritalin and how many hours does it last approximately when I take it?

I wasn't able to talk to my doctor directly (I had left him a message and he had spoken to my gf); what kind of dosage should I take compared to the adderall? Each ritalin tabet is 10 mg.

Any input from personal experience etc. would be highly appreciated. I have been taking adderall/amphetamine salts for 3-years now so I am just a little worried to how my body is going to react. Thanks again for all your help and glad to be a part of this board! :)