Different scale outcomes

Barb
At home my analog scale said 144 in April 
before getting pregnant in May 
At home analog scale said 152 when I was missing my period in July
On the digital doctor scale on the July 17th at my 1st prenatal appt it said 162.3
On the digital doc scale on the 10th it said 161 at my appt for my blood pressure 
On the reg old doc scale on the 21st at a ultra sound appt it said 174
On the reg old doc scale in the Wic office on the 24th it said 172
At home my analog scale today said 150
Hmmm which scale is accurate it's so hard to know for sure, what scale do u go by?