I have a number of thoughts. I'm going to be straightforward with you, but please do not infer that to be discouraging or rude. Much of what I am going to tell you is offered so that you don't waste a lot of money tilting at windmills.
First, before you spend a lot of money trying to retake classes to raise your GPA, check with the school that granted your degree. Some universities will allow you to raise your GPA this way, but there are a number of places that "lock" your GPA once your degree is granted. If that is the case, they will happily take your money, and all the great grades in the world won't help you. In any event, the transcripts from almost all universities will reflect both grades you earned in any given class.
I suspect it is possible that what you were told by that counselor may be based on more than just your cumulative GPA. Therefore, look at your undergraduate transcript, paying particular attention to the grades you received in the science classes, like A&P, pathophysiology, chemistry, as well as your math classes. If you received B's, and particularly C's in these classes, then the counselor you spoke to is probably correct. The practice of anesthesia is grounded in hard science, and the education of nurse anesthetists is almost entirely an education in science. If you struggled with these classes in your undergraduate program, that is a strong indication that you will not do well in anesthesia school. Schools are unlikely to admit a student who has a high probability of failure, and folks who did poorly in the science portion of their undergrad studies have a very high probability of failure.
There are a lot of nurse anesthesia programs out there, and each has it's own criteria for admission. For some, applicants' GPA's are the first discriminator. If the school you are interested in has such a policy, then your chance at getting an interview, much less being accepted, at that school are slim. For every slot in every anesthesia school, there are always several applicants. Therefore, if GPA is the first absolute discriminator, you may very well find you are not competitive.
On the other hand, many schools consider several factors beyond the GPA. For example, they will look at your grades in the science classes, at your grades in the nursing program, where you have worked, and your scores on the GRE. If you had a 3.2, but graduated 10 years ago, and recently took the GRE and smoked it, they will consider that as well, and you may very well get an interview. Then, whether you get in or not will strictly depend on how well you do in the interview.
No school that I know of allows you to apply for free. There is always an application fee, and that fee is non-refundable. So, before you spend a lot of time getting paperwork together, and spend a lot of money applying to various schools, call the schools you are interested in. Where ever possible, speak to the program director. Failing that, speak to someone involved with the applications committee. Tell them your situation, being very honest about your grades. Listen to what you are told. Then apply to those schools that are not likely to cash your check for the application fee and throw your application in the trash.
All too often, people in today's world want to believe you can be or do anything you want if you want it bad enough. In my experience, that simply is not always true. You may want to fly for the Navy worse than anyone who ever lived. But if you have less than 20/20 vision, then all the desire in the world won't get you there. In the same fashion, you may want to be a CRNA worse than anything, but if you simply cannot compete with the application pool, then you can spend a lot of money chasing an illusion.
Again, I am not trying to discourage you. If, after reading all I have written, you still want to try, then I ENCOURAGE you to go for it. At least two posters here have attested to the fact that it is possible to get in with a GPA similar to yours. But I encourage you to be honest with yourself.