Is it normal to have one lower central incisor? I only have 3 out of 4 central lower teeth between cuspids.

I would go slow before exttracting all your teeth.  There are many courses of treatment that can save your teeth (all or some)  The alternatives to your own teeth are dentures, implants or no teeth.  Frequently you can use compromised teeth to support an over denture.  Have...

I would caution as you move forward to follow the rule "Do No Harm".  There are many ways to reposition  the teeth or reshape them with veneers or bonding.  The fact you say you have a lot of money to spend makes me nervous because you may find yourself buying expensive treatment...

Invisalign is only one approach for orthodontic treatment.  Conventional orthodontics opens up many types of treatment.  The DNA Appliance can usually grow the upper jaw and make room available for a better final result.