Welcome to the board. As you indicated that you did have serious anxiety in the past which led to your being housebound for a year and taking medication which, now, doesn't seem to be helping, you have a history that must be explored.
Since you indicate that you are now working and 21, I am wondering if there have been things happening at work or in your personal life that may have caused you increased stress or concern. Remember, anxiety may come from genetic factors or things in the environment and we need to consider the environment here, I believe. Of course, not all medications continue to work, but that doesn't mean that you need to either switch your medication or be on the medication. Some professionals believe that medications can be used for up to one year and then, if needed, a bit longer. But at certain points in time the medication may lose its effectiveness because of changes that will occur in your body.
The 1st thing I think you need to do is to take a look at what might be happening in your life, take a look and see if some lifestyle changes should be considered too. When I say lifestyle, I'm referring to how much sleep you get, your diet, how stressful your job is, the quality of your relationships, whether or not you get any exercise during the week, etc. All of these things together make for a healthier life and can contribute to either you're feeling good or anxious. Any one of them, sleep and work stress in particular, can cause this anxiety to bubble up as you are describing it. So, consider if lifestyle changes might be in order.
We also have some things in our Tips column that may be of use to you. Specifically, I am referring to the video tutorial we have on relaxation breathing and the simple exercises that can be done in your home or even in your office.
You might also ask your boyfriend to take a look at the National Institute of Mental Health (http://www.nimh.gov) where they do have booklets online that describe panic attacks. This will give him a much better understanding that this is not drama but real.
I hope things do improve for you and that you feel much better very soon.