There are witches who follow a Christian path and incorporate magical practises into their work (try having a look at the excellent Christian Witches FB page) and they seem to harmonise the two elements very well together. Obviously as a practising Catholic there may be some areas of magical practise that do not feel "right" to you and you may prefer to avoid the darker areas of cursing and hexing. But in terms of exploring a love of the natural then I personally do not think it goes against what you believe as a Catholic.
But I would also add that while witches may well believe there is nothing wrong with the blend of witchcraft and Catholicism, the Catholic church may have a very different idea. I looked up their beliefs on the internet for you and found this statement by the Catholic church:
"All practices of magic or sorcery, by which one attempts to tame occult powers, so as to place them at one's service and have a supernatural power over others - even if this were for the sake of restoring their health - are gravely contrary to the virtue of religion. These practices are even more to be condemned when accompanied by the intention of harming someone, or when they have recourse to the intervention of demons. Wearing charms is also reprehensible. Spiritism often implies divination or magical practices; the Church for her part warns the faithful against it. Recourse to so-called traditional cures does not justify either the invocation of evil powers or the exploitation of another's credulity."
I don't feel I can speak for the Catholic church but their opinion of magic doesn't seem very high. However, neither the Catholics nor the Witches have a monopoly on truth. We're all just feeling our way through the world and nobody at all can claim to have knowledge of any one true path. So my advice to you is that if you feel genuinely compelled to merge two belief systems on your own personal path, nobody can tell you that you are wrong to do so.