I have had thrush 3 times this pregnancy....and ive used pessaries every time. I got thrush well after the 12 week mark though....so i can understand your concerns at inserting the pessaries and only being 7 weeks.
BG's advice is spot on.....also i have been taking inner health plus (about $22 for 25 capsules). Its really helped with the thrush. I also have my yoghurt once a day now....havent had thrush for nearly 10 weeks now.....

Good luck.....