It depends. Active THC levels of above 5 ng can make the case difficult... That is the legal level in WA. If course, the levels in your system will very tremendously depending on age, frequency of use, fitness, and other genetic factors.
Another factor in your case is the sufficiency of evidence to arrest and evidence to get a warrant for blood.
While this may seem simple, recent caselaw (State v Martins) has suppressed evidence in cases similar to what you are describing... But a critical factor is the actual language of the warrant.
I have had many DUI marijuana clients who don't end up with a DUI, so it is certainly possible, but more factors than are known at this time need to be taken into consideration.
You should consult with a local attorney.
I am not an insurance rep and make no recommendation on any company.
Your chances of not getting convicted or getting the charge reduced go up significantly with a good attorney on your side. You are free to contact any of the attorneys on here to meet with and figure out who you are comfortable representing you.
I suggest you do so sooner than later.
I would consider all of us responding to you to be good attorneys to answer the first part of your question. As for the specifics, you will need to give an attorney time to investigate before giving you a more concrete answer. You can click on any attorney's profile and email or call for a quote. Good luck.
There is some new case law regarding blood draws that could potentially help you. Specifically, whether the search warrant that was signed to get your blood asked for your blood to be seized and/or searched... You likely won't know that until you get discovery. I would just call around to find an attorney in the area who you feel comfortable with. Where your case is filed can also factor in to how likely this is to get reduced. For instance, you're probably better off in Lynnwood Municipal Court than you are in SnoCo South Division.