It's a cute dooo for summer and it will grow out. Just think about how much easier it will be able to take care of when dealing with water this summer!
Jeannie used to have a post on how to trim a Newf. I prinited a copy and took it along to the groomer. You may want to see if you can find the post to take to your next groomer. (edited to add.. I see someone else posted another one above)
I will take mine to the groomers for bathing and brushing (mostly to have them handled by another person or if I have been really busy), but do all of my own trimming to try to avoid those issues. Then if I mess up the cut, I have no one to blame but myself (and boy did I have some bad cuts when I first started) LOL
Clippers aren't a bad thing when used properly on a newf. I have been trying to do her ears with scissors for years and cannot get them even for the life of me. So, I use clippers to do the bottom of Sadie's paws and put the spacers (usually the 3/4 ") to even out the upper part of her ears (down to towards the tip. I don't go the whole way up). I still trimn the edges with scissors. The clippers help me blend it much better.
I also trim just the scraggly guard hairs that stick out with them. I never go down into the main part of her coat. It saves a lot of time and helps a lot. If I trim too long with scissors, my fibro flares. Her feathers and such are still all done with scissors.
Most folks including several on here have seen Sadie and think she looks good. They probably never knew that I use them. When I use straight scissors and thinning sheers only, she was extremely choppy looking.