You are well motivated to quit tobacco,that is nice begining.there are drugs that can help.requires visit.but you can substitute your tobacco
need with nicotex chewing gum or niclonz lozenges used by "bite and park" method.this will take care of irritablity and craving.stop and start using subsitutes.help yourself and enjoy good health for life.
if you can learn and practice yoga i.e. asanas,meditation,pranayam
and excercise for 30 minutes for increasing attention and concentration.
If you are suffering from ADHD consequences you have to consult for drugs. fill free to ask more.