R ggplot geom_raster increase row height to avoid overlapping of points

Question

Hi ggplot and R experts,

A newbie here. I have a usecase where I am using geom_raster for better optimisation.

Here is the reproducible R script:

require(ggplot2)
library(ggrepel)
# Create the data frame.
sales_data <- data.frame(
  emp_name = rep(c("Sam", "Dave", "John", "Harry", "Clark", "Kent", "Kenneth", "Richard", "Clement", "Toby", "Jonathan"), times = 50), 
  month = as.factor(rep(c("Jan", "Feb", "Mar", "Jan", "Feb", "Mar", "Jan", "Feb", "Mar", "Jan", "Jan"), times = 50)),
  dept_name = as.factor(rep(c("Production", "Services", "Support", "Support", "Services", "Production", "Production", "Support", "Support", "Support", "Production"), times = 50)), 
  revenue = rep(c(100, 200, 300, 400, 500, 600, 500, 400, 300, 200, 500), times = 50),
  status = rep(c("Low", "Medium", "Medium", "High", "Very High", "Very High", "Very High", "High", "Medium", "Medium", "Low"), times = 50)
)

sales_data$month <- factor(sales_data$month, levels = c("Jan", "Feb", "Mar"))
month_vector <- levels(sales_data$month)
number_of_enteries <- nrow(sales_data)

sales_data$status <- factor(sales_data$status, levels = c("Low", "Medium", "High", "Very High"))
sales_data$month <- as.integer(sales_data$month)

ggplot(sales_data, aes(x = month, y = dept_name)) +
  geom_raster(data = expand.grid(sales_data$month, sales_data$dept_name),
              aes(x = Var1, y = Var2, width=1, height=1), fill = NA, col = 'gray50', lty = 1) + #default width and height is 1
  #SAFE: geom_point(aes(size = revenue, col = revenue), 
  #           shape = 16, position = position_jitter(seed = 0), show.legend = F) +
  geom_point(aes(size = status, colour = cut(revenue, c(-Inf, 199, 301, Inf)) ), 
             shape = 16, position = position_jitter(seed = 0), show.legend = F) +
  scale_color_manual(name = "revenue", 
                     values = c("(-Inf,199]" = "red",
                                "(199,301]" = "#ffbf00", #amber
                                "(301, Inf]" = "green") ) +
  geom_text(aes(label = revenue), size=4, vjust = 1.6, position = position_jitter(seed = 0)) + #try with geom_text

  theme_bw() +
  theme(
    axis.title = element_blank(),
    axis.ticks = element_blank(),
    plot.background = element_blank(), 
    axis.line = element_blank(), 
    panel.border = element_blank(), 
    panel.grid = element_blank(),

    axis.text = element_text(colour = "blue", face = "plain", size =11)
  ) +

  scale_x_continuous(limits=c(0.5,3.5), expand = c(0,0), breaks = 1:length(month_vector), labels = month_vector) +

  # Remove extra whitespace from y-axis so lines are against the axis
  scale_y_discrete(expand = c(0,0)) +
  # Add straight lines at each factor level, shifted left/down so they're between values
  geom_hline(yintercept = as.numeric(sales_data$dept_name) + 0.5) +
  geom_vline(xintercept = as.numeric(sales_data$month) - 0.5, color = "grey")

Output Plot: As, one can see that, lots of overlapping is there. I have 2 questions here:

1. How we can increase the height of row so that there will be more space for geom_point. Can we use facet_grid in this case ? I am not sure here, how and whether to use facet_grid

2. Is there any other way than position_jitter to randomly plot bubbles so that they don't overlap ?

Please help ! I am sure this question will help many beginners in future as it is not addressed anywhere in SO or other platform.