You can easily keep current order while converting to factor with fct_inorder(), see this example:
library(tidyverse)
sample_df <- data.frame(
stringsAsFactors = FALSE,
Nad_Frequency = c("W1","W2","W3","W4","W5",
"W6","W7","M1","M2","M3","M4","M5","M6","M7","M8",
"M9","M10","S1","S2","S3","S4","S5","S6","S7"),
Nad_Totals = c(550.6233863,553.5625904,
563.0517622,563.6506493,566.7065001,563.8054161,
561.7409152,572.6378529,573.9247763,509.9807722,561.8506329,
579.9562373,564.9121329,592.8302856,585.6264275,
559.6527,549.3891637,565.1179935,566.2964748,563.2220424,
559.6463513,562.8478125,562.7622964,563.8086893)
)
sample_df %>%
mutate(Nad_Frequency = fct_inorder(Nad_Frequency)) %>%
ggplot(aes(x = Nad_Frequency, y = Nad_Totals)) +
geom_col()

Created on 2021-08-23 by the reprex package (v2.0.1)