Found The Trust And Will I Was Never Suppose To Find.

Long story short my grandma made a will and trust over 20 years ago leaving me a property that I was living in at the time and still live in to this day in California. Its controlled by the trustee my dad. There were 2 beneficiaries to the trust myself and soon to be born step brother( got 2 more step siblings in 2013). This property was to be gifted to me after she passes if I was at least 25 with some generation skipping trust transfer mechanism. Along with money to pay for education, to start a business, buy a home, maintain and repair the home while it's under the trust etc. if needed. My grandma passed away in early 2010 I attended her service with my dad and his new wife and step brother. And I was never told about any of this or receieved any information the only reason i knew it existed was because my grandma told me the last time i saw her 2009. (she lived in another country so visiting wasnt an easy task.) I just found a copy accidentally a few days ago and am learning all this just now. This whole time my dad has told me this is my house but now we haven't talked in 4 years because of this issue if I bring it up he literally would walk away and his wife would say she's working on it for years. I've reached out to a couple of attorneys and am waiting to hear back from them. At this time all the assets in the trust are all under dad and hes added my step moms name to them all. But is there a chance I'll be able to get what I was suppose to get? What challenges should I expect? I'm so overwhelmed.