OK, just checked your other posts and see you were in the UK, and that you had a D&C or at least one was planned. So at least you are not going to have to threaten the only free clinic in town with legal action to get some help, as you would in the US if you had no health insurance.
Definitely go get two hCG tests at least a couple of days apart. Even if they are giving you a lot of talk about your period coming, they can hardly deny you the tests that will tell you if you have vascular placental tissue in there or not. (And those tests would also tell you if you by some chance have a new pregnancy going on.) If your numbers are above 5 and not going down, tell them you really think you need the D&C, that you don't think you will ever get a period if your body is thinking it is pregnant. Having retained products of conception in your uterus is a great way to get a whole bunch of undesirable scar tissue.
If the sac had not grown and you are sure you were 11 weeks along, you don't have to torture yourself about them supposedly seeing a heartbeat. If you KNOW you were 11 weeks pregnant and all they saw was a 5-week embryo, that is a pregnancy that is doomed to end.
If you still have retained products of conception, it is possible that a period won't come, if the placental tissue is still what is called "vascular." That means it is normal tissue with blood flowing in and out and keeping it alive. If you have that, you will probably have enough hCG in your system to give you a positive reading on a pregnancy test, and if so, you won't have a period.
It does sound like you were not getting the best of care, at the very least the clinic should be following your hCG levels to see if they drop to below 5. If your hCG levels stay higher (mine were in the hundreds for three months while I waited for methotrexate and other things to work) you won't get a period, as you say.
Go to a new doctor, would be my recommendation. If you have no insurance, and have to go back to the same clinic for financial reasons, go back and insist that you get your hCG tested at the least. If they won't help you and they are your only option, you could tell them that you are considering getting legal counsel because you are concerned that their casual care might damage your overall fertility.
Sorry u r going through this. With my first m/c I had a d and c. They didn't get everything and had to have another. I know what u r going through. It may not seem like it now but it does get better with time. I am sorry for ur loss and good luck to u.