Your question does not make clear if you are talking about Juvenile court in the State of Washington or some other court or jurisdiction. It is also unclear whether the "diversion" was successfully completed. It might be wise to check with the court to make sure everything was completed. Also, wherever the record is, it is unlikely the court sealed it automatically on their own initiative without a motion from you or your attorney. Similarly, if whatever you did in court involved a loss of firearm rights (DV?) as you suggest, a motion is usually needed to restore those rights. It would make sense to ask an attorney to look at what happened and make any appropriate motions rather than risk purchasing and possibly illegally possessing a firearm.
Call the court and ask if the records were ever sealed. If yes, they will not show up on your criminal history. In either case, neither of those charges, even with convictions, would make you ineligible to purchase a firearm.
If your firearms rights were revoked, you would need to petition the court to have them restored regardless of whether your records are sealed or not. However, it sounds like you may not have lost your rights if all you had were misdemeanor charges and you successfully completed diversion. You should contact the juvenile court to inquire about that. If needed, you can get a packet from the clerk's office to petition to have your rights restored. The packet should only cost about $20 and will likely come with instructions on how to proceed.