Failed medical abortion?

I found out I was pregnant last week and had my last four tablets for medical termination yesterday. I was told on Thur that I am between 4-5 weeks pregnant and because im so early that it might not work. Anyhow 30 mins after taking last 4 tablets, I had the unbearable excruicating cramps, I began to bleed really lightly for about 4 hours and since then havent bled at all, had the occasional cramps but thats it. I am so worried does this mean that its failed? I rang the nurse last night and she said give it till monday and if you havent bled any more than to ring up and arrange a scan and possible further procedure. I am soo worried please help!! xxx