6 days late 😭

so the last time I tested was when my period was 3 days late and it was negative I've been haveing light cramps on and off since 6dpo my period is now almost a week late and the suspense is killing me with my first I got a positive pretty early...I've been extremely tired and I feel sick all the time now I have an ultrasound to check on my ovarian cysts next week I want to test again but I'm afraid it'll be negative and I'll waist money on another test should I wait for the ultrasound or just test again any of you ladiess not get a positive test till later