I never really had to transition either because I was raised as a vegetarian straight from day 1 >w<
If you're cooking up a dish that would normally contain meat, sometimes you can replace it with potatoes/tofu/sometimes beans, or meat substitutes if you like those/are available to you. I know about the whole thing where they can affect your hormones, but surely if you eat them every once in a while it won't be that bad for your body Anyway! It all depends on the dish but it's good to keep those alternates in mind. So when Elin and I make curries, to bulk it up (and also have more for me to eat) we'll include his chicken and some potatoes for both of us and I'll pick the chicken out for him. Speaking of curries, a load of those can be turned into vegetarian/vegan if they aren't already off the bat, so with Indian/Vietnamese/Chinese/Japanese/Thai/I can't even list all the different variations here you'll have plenty of selection ^^ I loooove my butter chicken curry and tikka masala, and Japanese curry too. But I've barely scratched the surface when it comes to that whole world of food so there's a whole bunch of discovering I still have to do!! Also, quinoa is fantastic as well and it's delicious. Loaded with fibre and protein!! I'm sure you'll be able to find some sold in bulk at a great price.
Eggs don't contain lactose and shouldn't really be considered dairy, so if you aren't going vegan because of the whole "absolutely nothing that comes from an animal" reason then I'd say keep eating those :0 Great source of protein and other important nutrients!!
I think the hardest part which is mostly just an inconvenience, is that when you're going to restaurants with friends (hell, even chain fast food places), you should definitely check their menu beforehand and see if they'll have anything you can eat there. It's mostly an issue with family owned joints but it's still an issue you can run into. Even today some places don't have any proper vegetarian/vegan options and you'll be stuck eating whatever appetizers instead of an actual meal. Like hell, a McDonalds near us decided to stop selling their vegetarian wraps. so outside of I don't know, asking them to make me a burger but hold the meat or getting an overpriced salad, there isn't really much of a selection for me at that specific location. At least a different one still has their Mediterranean wraps lmao