How do you plan for ground up construction

[Nirmaldeep Brar]

Hi, I am a healthcare professional with currently renting office space. My rent is $1000/month. My revenue for last year was $1M. I have land that I purchased last year and would like to build a 6000 sq ft building for my dental practice. I have limited space to grow at my current location so I would like little bigger space (3000 sq ft ) foe me as well as 3000 sq ft space to rent someone.  The land is approved for ~7300 sq ft space. My enquires are:-

1. Should I go with 7300 sq ft and try to get as many tenants as possible or stay within my comfortable financial position.

2. How do I calculate the monthly mortgage+ interest+ insurance+ tax that I should be able to comfortably able to take care.

3. My home mortgage is 4500/month, practice loan 4000/month, Student loan 1000/month.

4. My credit score is really good and I have around $450000 mortgage  on 2.75  rate for 18 more years.

Thank you

N. B