Speaking Mandarin in Taiwan

Well,I am starting classes in March so looking forward to.

Dear Priscilla

No.  I do not speak Mandarin, but I suggest for other ex-patriots to know Mandarin before they come to Taiwan because the Taiwanese have a limited ability with English.

In my case, my roommate is bi-lingual so she acts as my translator all the time.

As for schools where you can learn Mandarin, there are several of them posted online. Check them out and choose one.

More people know English than let on. I studied for two years and only cracked the surface, but with teaching it allowed me to bond with the kids. TLI (Tapei Language Institute) has a great program and have offices in Taipei, Taichung and for all I know elsewhere. The people are great, unassuming, work hard and mind their business, something Americans can learn/relearn. Hoklo is the indigenous language, Hakka and many more. Stay a while, staycation and eat starfish, sea slugs and pigs ears!

After living in Taipei for 6 years, I find that most Taiwanese are terrified of speaking English to a native speaker.   And after working with elementary school students for 6 years, I also find that the way they're taught English by people that speak it as a second language is counter-productive and produces students unable to communicate in conversational English.  Taiwan has a way to go in catching up with the rest of the English-speaking world.

But then I haven't exactly nailed down Mandarin either.

i don't speak chinese and i ve been here for 3 years now, even my wife is native chinese speaker

The adage "when in Rome do as Romans do" also applies to learning Mandarin in Taiwan if an expat aims to "integrate successfully."
But the reality is more complicated than that.
An expat with deep-pocket and inclination towards conspicuous consumption in Taiwan would find integration easy regardless of his/hers Mandarin skills. Such rule of thumb of course applies globally for obvious reasons.
Also consider xenophobia and racism, which undetermined numbers of Taiwanese possess overtly or otherwise. Hence "successful integration" in Taiwan is a function of an expat's ability to learn Mandarin and the Taiwanese he/she happens to encounter.
Of course being able to speak and understand Mandarin makes long-term stay in Taiwan more palatable,  meaningful without needing a local as crutch. Knowing how to read Chinese (including most signages) is also a definite advantage. 
Unfortunately the harsh truth is that only a tiny proportion of adult expats (minus the miniscule number of the linguistically talented) can achieve Mandarin proficiency to converse at the senior high level (or lower), and even less able to talk about issues as Brexit, trade policies, organic chemistry and the advantages of front-wheel vs. all-wheel-drive.