The first thing I'd like to do is to get a copy of the Pension Insurance Handbook in Beijing.

There is no longer a Pension Insurance Handbook in Beijing. You can ask the person in charge of your organization to go to the social security office and print out a copy of your personal contributions for you, and you can also check your contributions on the Internet.

Also, are you going back to Beijing? If you have found a stable and suitable job in Tianjin (the city of your domicile) and are sure that you will work in Tianjin in the future, and will not go back to Beijing 100%, then you can transfer your insurance back to Tianjin. How to do this, you human resources people must know. The premise is that you must be sure that you do not come back, because once transferred out, and then want to transfer back, is unlikely.