Dear Sapphire,
No, you are not doomed. Law is an incredibly competitive business and sometimes as a law student you can feel as if you are never going to get anywhere, but don't despair.
(1) Keep working on your grades, but work smarter not harder. Talk to your lecturers and tutors about what you can do to improve your grades. Generally the difference between a B and an A if you are really trying your best, is attention to detail, and giving your lecturers exactly what they want to see without any unnecessary detail. Many students excel simply because they are good at writing essays or exams. So work on your essay and exam technique. The biggest downfall is not answering the question properly or addressing the issues that they want you to. Spend a lot of time dwelling on the question you are being asked, and again talk to your lecturers about why you didn't get an A in previous essays.
(2) Get work experience - you can trump any student with better grades at an interview if you can demonstrate that you have solid prior experience in a legal environment. Can you get a part-time job in a law firm as a law clerk, research assistant, paralegal or secretary? This will have weight in getting a grad position. Or even volunteer to assist in such a capacity. Also many mid tier firms would prefer a person who is switched on, balanced, interesting and great to work with, over someone with an amazing GPA. A through the roof GPA can often indicate that a person has no life outside of their study or work which is not very attractive to prospective employers.
(3) Demonstrate your interest in law by joining legal industry associations as a student etc and getting involved in the industry before you graduate.
All the best!