The issue over conversions has been a sticky one for a long time. The problem is that according to Orthodox, even if Reform were to cover all the techincal requirements (which in many cases they don't)- the people conducting the conversions are not qualified to do so and do not qualify as witnesses. This means that no conversion takes place as valid witnesses are required.
Due to this, according to Orthodox your mother may be a righteous gentile, but she is not Jewish. Since your mother is not considered Jewish, neither are you. According to reform (and to most Conservative communities) you are Jewish. This split is historic and dates back right to the start of the reform movement in the 19the century. In many ways, early Reform was far more liberal than modern Reform and some of theior early decisions were reversed later- but due to the very liberal stance of many of the early Reform leaders, it was seen as a complete break from Judaism by the Jewish authorities at the time; and the Reform movement lacking in any halachic basis or having any legitimacy whatsoever within Judaism. For Reform to survive, they thus instituted their own rules and institutions, including conversion and ordination under their auspices.
You are in the unfortunate position that due to this split part of Judaism will recognise you as Jewish, and part will not. Thus peopel in Reform will tell you that you are Jewish- Orthodox willaccept you as part of the greater Jewish community- but not for religious purposes. If you want that acceptance from Orthodox, you will have to have a valid conversion from an Orthodox Beis Din (Rabbinical court). Unlike what someone stated- the conversion from reform to Orthodox is no different from converting from another religion to Judaism. You have the same syllabus to learn and the same need to demonstrate a commitment to living an observant Jewish life. However, it is often easier for those coming from liberal Judaism into Orthodox as they at leats have an academic understanding of many of the requisite items- even if they have a lot to learn about the details. You will at least know what the various holidays are and some of their symbols- though you will need to learn how Orthodox observes those festivals, the meanings behind them, and what the services are.
Yes- its a journey, but depending on you it cna be a jhoyous one or a long and rocky one- it all depends on how you view it and undertake it.