Firstly you cannot claim points for experience under different NOC.
Secondly SINP is very strict in terms of documents. They not only ask responsibility letter but can also verify with your previous organization.
Most people who are getting NOI with CRS less than 400 have either ties in Alerta or they are already in Alberta. You can try to increase your CRS above 400.
Don't worry normally SINP takes 4-5 months to give nomination. Always check your mails and don not rely only on oasis status because sometime they ask for verification or related documents through mail only.