create monthly 24/7 schedule

We have a schedule each month written in Excel the same way for years now. It's totally manual and I'm wondering if there is a better way for us to either create the schedule or help calculate our manual entries to make it stand out where we have too much coverage or not enough.

For coverage during the week, Monday through Friday, we need:
3 people between 7:00am and 7:00pm
2 people between 7:00pm and 11:00pm
1 person 11:00pm till 7:00am the next day

For weekend coverage, Saturday and Sunday, we need:
2 people from 7:00am till 11:00pm
1 person from 11:00pm till 7:00am the next day

Staff will work in a variety of the following shifts:
7A = 12 hour shift starting at 7:00am
D = 8 hour shift starting at 7:00am
E = 8 hour shift starting at 3:00pm
3p-7p = 4 hour shift starting at 3:00pm
7p-11p = 4 hour shift starting at 7:00pm
7p = 12 hour shift starting at 7:00pm

If someone has a scheduled say off, we will put a / the cell prior to filling the schedule in for the month.
If someone is Sick, the schedule will be modified with a S replacing whatever shift was originally entered in the the cell.
If someone has a vacation, personal or holiday time scheduled, we will enter a V, P or H followed by the number of hours being used for that day.

We currently manually count the amount of people scheduled to work each day and make a note at the bottom of the column if there is a need to be filled. This does allow for human error.
TIA

Hi, welcome to the forum.
You will have to use formula's like COUNTIFS() and SUMIFS()
helper columns at the end of the month with the codes you have as headers will serve.
I've downloaded the file and will see if I undersand the codes you use.
But start with formulas and funcyions