Google Flights displays flights that come in part via their advertisers, who pay them to display their flights. If you, as an airline/OTA/agency don’t advertise/pay the piper (Google) there is a good chance your inventory will not be seen. If you searching for a route that is not serviced by a major airline, and perhaps only by a discount or local carrier, you may find your flight search results are lacking for the full picture of cost-efficient air fares.
Likewise, if your Google Flights results do show you the fares and only offer to redirect you to the airline site, there is a very good chance you are paying above the best cost-efficient air fare rate, as no wholesale, consolidator, agent discounted fares are being included or offered for the search.
Google and Youtube are great places to learn about heart surgery, but best not to rely the online results from either to perform mission critical procedures. Likewise Google Flights is ok for a reference point, but you should not expect them to deliver the most cost-efficient air fares, rather they will return their advertisers best airfare offers.
Find a good travel agent and show them what you found. In most cases, they will find you a better price or deal. If you want to use an online booking site, as compared to a meta search engine, suggest you look to a full service IATA registered travel agency with an online website like Future.Travel, who have real-time seat inventory and live support for questions and solutions, two things that meta engines don’t provide.