I've also had some crazy readings at appointments pre- 20 weeks. At 17 weeks I jumped to 17x/8x, down to 150s with rest and then again at 19 weeks a 15x/8x. I take my bp 2x at home per doctors orders and trend anywhere from 11x/5x (common)- 13x/7x (rarer). From that everyone has felt (myself included) relatively confident that it had more to do with nerves (though I didn't feel nervous)/random spikes (we travel by plane for MFM appts). And have put a plan in place that if I start trending in the 140s to start meds.
So like the previous poster, getting a bp cuff for home might give you a broader picture of what your BP is doing normally (outside those pesky visits) that can help inform your team of when meds time might be if at all. I'm crossing crossables that we're able to go med free... and will do the same for you.
2008-Our Baby Girl, PTL born too early at 30w6d, Fought so hard... Forever Loved & Missed
2010- Lil' Bro, Pre-E at 29 weeks... Induced at 36w6d, Born 37w
2012- Lil' Sis, Super-imposed pre-e at 25 weeks, PTL & GD at 35 weeks, Evicted 36w