Olives, good for you for making some healthy changes! Since so many others here have given great advice on how to make a change to vegetarian, I’ll skip to offer some advice from a Buddhist perspective.
I’ve been vegetarian for 20 years, and attempted it for a decade before, at age 11. (I’ve posted this on the SD before, so hope the old timers aren’t sick of it) For me, it was seeing the fish that my marine biologist Dad hauled up when we were out on his teaching boats, and it hit me that the fish were dying, watching them gulp for air, flopping around. After that simple realization, I refused to eat them, and really stuck to it. Yet, I contnued to eat other meat, because the death connection hadn’t been made, and, at 11, yer kinda at the mercy of what your parents choose.
It took another 10 years to really “get” vegetarianism for me, and I educated myself on what would be a nutritious diet w/o meat. This was a time when veg food was just becoming available. The book “Laurel’s Kitchen” really helped me to understand the basics of nutrition, especially with whole grains as a staple. I’ll cut that short here.
Vegetarianism for ethical reasons has a long history in the East, and, quite varied in the parameters. I thought the Wiki entry on Buddhism/vegetarianiism a decent rundown. Basically, there’s no set rule for vegetarianism among the myriad of Buddhist sects. Some do, some don’t. In taking Buddhist precepts to heart, not being an expert, but working with what I understand, I chose not eating meat as trying to avoid hurt to sentient creatures. It’s a personal choice, and certainly aided by the luxury of living in the West, where it’s fairly easy to do so. A nomadic Tibetan doesn’t have that same largess of food, so has to do with what’s possible to survive.
Buddhism also deals with non-attachment, and that includes being too fanatical about your diet. I’ve dealt with that when being a guest at someone’s house, and they serve meat. There are different levels of that, but I then treat it as “Alms”, and, generally, accept the host’s generousity gratefully.
I found this article to be interesting, a bit of history of Buddhist/veg practice in the West.
Just do what you can do in making changes, and understand it as you can. For me, it was realizing aspects of not doing harm on different levels, making connections, and making decisions. As well as learning cooking techniques and dealing with what was available to have a healthy diet. I can say that it is way easier to do now than it usta be.