There's quite a bit to unpick here as you seem to have been advised to do some of this incorrectly by the nurse.
You've been advised to use a sequential (a cycle) form of HRT. This will give you a false period every 4 weeks. It's called a withdrawal bleed. It's not your own period. This happens when you stop the progesterone.
This type of HRT is estrogen every day and 200mgs of Utrogestan (that's 2 tablets, not 1) for 12 days a month.
As you've found out, it's hard to start the HRT cycle when your period is AWOL!
The way round this is to start the Utrogestan on the same day every month, regardless of when your period is due (and maybe won't turn up.)
As you've now been on gel for almost a month, it would be a good idea to start Utrogestan some time soon. So, if you choose to start it (for example) on the 11th Sept, you'd do 12 days, then repeat from the 11th October, etc.
Be prepared for a few hiccups along the way as it can take time to settle into a new pattern. You may have no 'withdrawal bleed' for a while, or have 2 periods in a month (your own and the HRT withdrawal bleed.)
Don't worry if this happens, just carry on and keep to the same dates (as above) and it will settle down.