Add new Rows which sums & counts values

I do not understand exactly what you mean by

However I guess you may be having a problem with the NA's in March. Try this:

wd   %>%  group_by(Month) %>%
summarise(Total_Cal = sum(Calories, na.rm = TRUE), days = n())

For a new question please supply your sample data in something like dput() format (?dput) or have a look at FAQ: How to do a minimal reproducible example ( reprex ) for beginners

I hope this helps.