In 1995 then Poland was already on the track to EU membership
Poland's main trade partners i.e. Germany, Netherlands, France, Italy, etc. are the same now as they were 20, 30 even centuries ago. EU didn't form those partnerships - trade with those countries has been in Poland's history for ages.
Being 'on track' or even having EU membership doesn't suddenly make other countries including EU countries drastically increase trade all of sudden - if that were true Romania, Bulgaria, etc. would be far richer and their exports should've increased dramatically, but of course they did not. It was a minor gradual increase, which they would've likely achieved without the EU just like Poland. The only thing that Poland got was 100 billion EU which hopefully the w Europeans will continue to give us so we can fix our sidewalks, build roads, paint gyms, and give contractrs to polish friends.
Trade with China is very small compared to trade with the EU.
The point is that the GROWTH in trade, as PROVEN by the data/links above, is not with these traditional partners but rather eastern European countries, Asia, M.E.