Yes, you absolutely must weigh all your ingredients in weight.
I know it takes a while to get used to especially with the liquids, but you'll get the hang of it.
Even FO's must be weighed.
I used to weight lye and measure by volume water and oils, soaps came out nice , but then I read that I should weight everything and tried to do it that way twice. The soaps came out toooooo oily. And I only used 1% superfat.
Weight everything except water which weighs the same amount as it measures.
At 1% SF you are really risking a lye heavy bar because you have absolutely no room for error. What recipe are you using that you are ending up with an oily soap and how long are you letting it cure?