Blood pressure & exercise correlation?!

Ta
Am 17w & saw my OB today and he wants to see me again in 2 weeks as my blood pressure was 129/92. Pre-pregnancy, I always had low bp (110/72) so I'm ok with keeping an eye on it since am a FTM@40 and I don't want to develop preeclampsia.
 Weird part is that when they weighed me, I've lost 5lbs since my appointment 4 weeks ago (am still 7lbs below total). Baby has a strong heartbeat and is doing well 💕
I eat 2400-2900 cals of a pretty healthy diet (since I've been told to gain 25-30lbs) and I walk daily (3.5miles but not all at once!). This is my rainbow baby and I don't want to mess this up! My OB has suggested that I cut back on the walking (huh?). I thought that gentle exercise such as walking was good for preventing high blood pressure? I'll have a more in-depth discussion with him in 2 weeks but what can I do to keep my bp from creeping up?