Hello,
I have been working as Magento-2/API Developer from last 6 years. I am true expert in API Integration, Magento-2 Development/Customization, Magento-2 Modules, Themes, Frontend/Backend etc and can handle any task/issue related to it. I already successfully integrate api's in magento site and handle any task related to it. I have gone through your requirements very carefully, I can easily help you to integrate payment gateway of instamojo and payumoney to magento 2.2.4 site running on custom theme and complete your all requirements as mentioned in description.
Can you please let me know once you're here? I have some queries and wants to discuss with you.
Regards;