The throughput you are seeing is normal. When you combine the links, you get double the bandwidth, but not double the speed. You would see increased throughput in a situation where there were multiple TCP conversations to a server where the links were aggragated. For the way you are using the network connection, your data transfers will not be any faster.
IEEE 802.3ad Link Aggregation (LAG): what it is, and what it is not presents more information about how this type of teaming works.
No matter what type of team you choose, you cannot increase the speed of the connection you have to 2 Gbps by teaming the ports.
Have a great day.