Mobile App making

I'm looking to have a mobile app developed for both iOS and Android. The primary purpose of this app is booking appointments and get paid with two options online payment and offline payment. If it's offline payment make strategies how to collect money from centers that will be included in app. The main idea to be discussed with the chosen developer.

Key Requirements:
- Cross-platform development for both iOS and Android
- E-commerce functionality with appointment booking and payment processing
- Strong understanding of E-commerce app features
- Prior experience in developing similar mobile applications

Ideal Skills:
- Proficiency in mobile app development
- Knowledge of E-commerce systems
- Expertise in iOS and Android development
- Excellent problem-solving skills and attention to detail

Please provide examples of your previous work related to mobile app development in your proposal.