I arrived on a Saturday expecting to fly Monday, it happened to be the Tuesday (I’ll call Day 1)
Had you completed your TSA fingerprint submission in your home country before you arrived in the US and received approval to commence training?
If not - then you cannot simply arrive on a Saturday and expect to fly. You have to wait for the TSA to formally advise the Flight School that you can commence. That can take 3-5 days.
Before arriving I was assured I would be averaging about 3.5 hrs a day,
To average 3.5 hours a day would be hard work and can be extremely difficult and tiring for a new student to absorb.
To complete in 21 days - you only need around 2 hours a day of training as your solo cross country's would cover the additional.
Before going I would liked to have known more of the facts,
20/20 hindsight. You need to do your due diligence before trusting your cash with anybody.
Had you completed all the written exams before arriving in the US?
I wished I knew before beginning the process just how unlike a bed of roses my trip would be.
Sorry but that falls fair and square on your shoulders.