Hi, I'm not entirely sure if I have ASD yet, or at all, but I have been diagnosed with ADD and I thought I would chime in. Ritalin is composed of two drugs, one active, and one which is either non active or if it is, hardly at all. I am prescribed 15 mg of Focalin Extended Release, which is the same drug as the active one in Ritalin. My dosage could be viewed as about 30 mg Ritalin. For me personally, it helps only a little in motivating you to do something, but once you begin to work on something, or do anything for that matter, you get tunnel vision and are focused only on that thing. Also, if you are doing something mentally exhausting or boring, it is easier and less draining to complete. Many people have issues sleeping, but I take one pill at about 8 am and have no trouble sleeping by 11 pm. It can make food seem unappetizing/make you feel full, so if you have existing eating problems take caution. If you have a lot of mental chit chat or rapid and incomplete thoughts, it can really reduce that. It's strange having a quiet head.
Ritalin, Adderall, Focalin, etc... are all lucrative drugs and many doctors will push you to a high dosage or not monitor you properly. If you do decide to try it, make sure you start small, my doctor started me on 5 mg, then 2 weeks later 10, and while I'm currently on 15, I have been experiencing anxiety and have been slightly panicky which is not normal after a few days of getting acclimated to the medicine so I am going back down to 10. The first 3-4 days on a higher dose can be rough but your body gets used to it and then you should feel better. Also, you can't really drink coffee on this unless you want to be bouncing off walls followed by hard crashing. It really is legal speed, and is a Schedule II drug, along with being chemically similar to meth. Personally, I would only use it if you need it for a job or for some kind of schooling, but it is worth looking into.
Just some things to think about.