I also have this and currently 39 weeks pregnant, I had a couple of outbreaks mainly in second trimester and like you was worried. I spoke to my doctor and also a consultant and they both reassured me that as I had had it for 4 years there was no risk to the baby while she was in the womb, the only risk is during the birth like previous posters have said and even then if you do happen to be having an outbreak and deliver naturally the risk is very small as baby will have received antibodies from you.
During my outbreaks I didnt take any tablets as luckily they were quite minor and sorted themselves out within a few days, if I had any severe outbreaks I would have taken a course of anti virals as it's safe during pregnancy (and also breastfeeding). From 36 weeks I've been on suppressive therapy (400mg acyclovir 3 times a day) and will continue to take this until she is here and probably for a week after just to avoid any discomfort of getting an outbreak days after birth!
I spoke to a consultant twice about this but at my last appointment with them at 36 weeks they discharged me to midwife led care and reassured me again that the risk is something like less than 1% transmission to babies during birth and this is more likely for those people who don't know they have the virus and unknowingly have an outbreak at the time of delivery. It's also a higher risk if you get the virus or a first outbreak during pregnancy, specifically 3rd trimester, as your body will not have had time to develop antibodies (even then still quite small in the grand scheme of things).
So the position you are in is the safest one possible as you are aware of the virus and know the symptoms of an outbreak, you can also ask to be put on suppressive therapy from 36 weeks to put your mind at rest in the run up to birth.
I would agree with a previous poster that it's quite hit and miss with how much your midwife might know about the virus, one of mine didn't know anything and made some sweeping statements but the other two were very unconcerned and happy for me to take the suppressive therapy and birth on a midwife led unit. Talking to a consultant will really help, I found it beneficial to write my questions down as I generally forget to ask certain things when speaking to doctors haha!
Sorry for the massive essay but I feel really strongly about this subject and hate that it's such a taboo topic so can be quite isolating. The main thing to focus on is that baby is safely tucked away in a protective sack, antivirals are safe for use in pregnancy and that the fact you have had it for so long and aware you have it means there is very little to no risk of transmission during birth, even less so if you take suppressive therapy in the run up!
Feel free to PM me if you're ever worried or concerned as speaking to others about this really helps and I know this forum really helped me in the first few months. Just try and relax and remove as much stress as possible
take care!