Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
So yeah sometimes it takes a while. Try not to get discouraged.
That said, though, every time I've had to re-start warfarin after going off for surgery (something I did twice in 2011), it usually takes several months to get back solidly into range again. And that's even going right back on the exact same dose that I was on before surgery. It's very weird.
I used to take 6mg a day and had been doing that for a couple of years, but earlier this year, that dose was suddenly too much and my INR was bouncing up close to 4.2 or so. We cut back to 5.5 and it was fine. No telling why my dose suddenly changed ... it just did. Guess that's why they like to monitor us on a regular basis!
I guess what I'm saying is not to stress it too much. Warfarin is finicky and it can be hard to get to the right dose right away ... sometime it just takes a while, but it sounds like they are narrowing in on a good spot for you.