It looks like you are over-paying for a lot of services. Like someone else mentioned, for starting out something like Linode or Digital Ocean would be cheaper. (and they don't charge for bandwidth until over 1 TB I believe)

Also, 8c/message for SMS is very high. Twilio has international SMS service that ranges from .75c to around 3c a message. (disclaimer, I have interned there)

On the implementation, it also seems like a NoSQL DB like MongoDB might not be the best choice. This is because it seems like you are dealing with a lot of relational information, which is significantly more complicated to implement in a non-relational database that is not designed for that.

These are just my opinions. I like the front-end design!