Serverless has to create a bunch of “background” resources to glue the other resources (e.g. functions, methods, etc) together, so there’s definitely going to be more than you think.
The best way to see all the resources is go to the CloudFormation section of the AWS Console, select your stack and go to the “Resources” tab.
Here’s an AWS CLI command will print out an ordered summary of how many of each resource has been created:
aws cloudformation describe-stack-resources --stack-name [YourStackName] --query "StackResources[].ResourceType" --output text | tr "\t" "\n" | sort | uniq -c | sort -r
I’d be interested to see what you’ve got, if you can share.
Unfortunately I think you’ll still be left with few options: A) Split in to multiple services B) Re-use functions for multiple endpoints 
Update: I realised the first version of the command I gave you didn’t work…