Unless you're having incapacitating pain, your body is doing what it needs to do to adjust to the loss of the pregnancy. Even with an ectopic pregnancy, your body produces hormones and reduces other hormones. The fact that your levels have gone from 7000 to 291 indicates that the pregnancy is gone. It just takes time for your body to adjust.
Find ways to relax and let nature take it's course. My daughter had an ectopic pregnancy last year and went thru the same thing. Her doctor did do an ultra sound before administering the drug so that he would know where the pregnancy was and if it had already done any damage. I'm sure your doctor did the same.
Also keep in mind that the drug is strong and has it's own side affects. I'd trust the doctor unless your pain is so intense it doubles you over or you hemorrhage. Having either one of those happen is extremely unlikely.
What is important now is to be kind to yourself and your body while it heals. Focus your attention on other things while also allowing yourself to grieve the loss of this pregnancy. It's easy to focus our grief on the physical pain instead of the emotional pain. Feel the sorrow. Find ways to relax. And do and think about other things too. Find a balance.