I have been a lot of opportunities to meet several people and speak to in English than before.

Could also rephrase:

"I had a several opportunities to meet people and speak in English"

Last week, I went to a international party.

I have been had a lot of opportunities to meet several people and speak to in English more than before. (It is not clear if you had a lot of opportunities to meet people or a lot of opportunities to speak English or both... Maybe you could say "I had a lot of opportunities to meet English speakers and speak in English more than before.")

Talking with people at noisy bar with while drinking beer makes it harder to get understand what people speak are saying in English as I loose concentrate my concentration on English.

However, drinking too much beer, wine, and vodka... and all of sudden the Time has come!

"Oh I understand it all! That`s kind of magic!! How fun it issss!!!"

Yep, no magic. It was just going crazy with drinking too much.
I don`t want to remember of the headache next day ^^;