Anyone Else a BDM on the road with work and pregnant?

[1stNonFurBabyOnTheWay]

I am a Business Development Manager who covers a large area of the country and travels a lot for my role.
I am 22 weeks pregnant with my first child, and have had very bad symptoms, starting with severe sickness wk1 -20, and started suffering bad episodes of dizziness, feeling faint and extreme fatigue recently.
I told my midwife and they said its my body's way to tell me to slow down and take things a bit easier. (My husband rolled his eyes at this!)

As it is my first pregnancy, I really do not know what I am doing or what is best for baby and me.

I am a natural work addict, and work hard in the male environment I am in, and have no one in the same role who has advice to help.
I do not want to look like I just want an easy life, but I am really starting to struggle and it is worrying me, especially when I want to return to work and have a career with this company.
Any other women out there who are in or have been in a similar situation?
When do you start to cut down driving?
When do you go off the road completely? (this is fitting behind the wheel dependant obviously!)
How do you prove you are still serious about your job?

Any advice gratefully received.

I am field based but not a huge distance. Managing 15 small locations.
I have found it so hard generally to be an effective manager whilst I have been feeling so ill.
I use to start earlier and then do admin for an hour or so in the evening. Because I am literally doing 9 until 5 now I am struggling to keep up. My use of time during the day is not very effective either as I am slower and less interested because I feel poorly.
Our senior management team have very high expectations of us and at the moment I am not as in control of the workload as usual so feeling like I am doing a rubbish job over all compared to usual.

I am 13 weeks so I am hoping it will ease off soon.

I feel your pain though. Have you spoke to your Manager?