I have reviewed the WA resources and from what I can determine, a fair amount that you have listed in your question would be subject to use tax if sales tax was not charged. The only exceptions I can determine that are not subject to use tax would be Website development, but not the hosting and services and the professional services you mention. All other items you list would, based on the what I can determine, be subject to use tax if there was no sales tax charged initially. Also, if sales tax was charged, but in an amount that is less that what the State of Washington would charge, you would owe use tax for the difference.
The links below may be of assistance. From your question however, it appears you may have already reviewed them.
WA Tax Reference Manual
Sales Tax List
Use Tax
@shanenc
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
