I also had lyme for about two years before being diagnosed. Throughout the last two years, I have been either working or in school the whole time. However, it wasn't until January of this year that things got really bad for me- and at that time, I was working a very easy job. Even still, I would work, and then go home and sleep, sometimes right through supper.
I'm back in school now, and I can completely sympathize with what you say. It is absolutely exhausting some days just to remember all the medications I have to take. I dropped down to a reduced course load this year, something I would never have considered even two years ago. In fact, the first year I had lyme (but didn't know it), I forced myself to do a full course load at school, and ran myself into the ground and had a breakdown at the end of the year. Now- well, I'm taking a reduced course load, and to be honest, I often feel like I just want to quit altogether. Instead of daydreaming about normal things, I dream about being able to stay in bed and sleep all day...and just stay there for ever...haha
Just don't commit yourself to anything you cannot keep up. I almost signed up for a full course load, because I was hoping I would get better- but the problem is, Lyme has so many ups and downs, and herxes from new antibiotics, and you have to plan for the worst days, not the best. However, the few people I've talked to who had the same time between infection and treatment, all generally started to feel improvement by (or before) the six month mark. So while you have to accept that you may not feel better in the next month or two, you will see improvement eventually.
If you are running yourself into the ground with your work, maybe you need to consider cutting back somehow. Could you switch to part time? Or reduced hours? Does your work have someway to work from home? Even if your company just lets your do it as a short-term thing, (say for a month, or 6 months, or whatever they will agree to), it could help you a lot.
I'm not trying to be depressing- I do believe you will see improvement, and it could happen as soon as in the next month, but I know what happens when you push yourself too hard. Treating Lyme is more like a marathon than a spring- so you have to pace yourself.