Microservices testing: how do you test interactions between services?

testing interactions between microservices has become a major pain point for our team. we're dealing with about 8 distinct services in our main application flow, and ensuring they work together correctly is tough. we've tried various approaches: contract testing with Pact, integration tests that spin up real services in Docker Compose, and even some lightweight service virtualization. the main issue is balancing coverage with CI build times. our full integration suite takes about 45 minutes to run because of the setup involved in getting all 8 Docker containers initialized and configured. we want confidence, but we also need fast feedback. what are your strategies for effective microservice interaction testing? any tips on optimizing these kinds of tests or approaches that offer good coverage without prohibitive execution times?