I was vegan for 12 years. Dropped 15 pounds right away and kept them off till I worked at a veg. deli/bakery. The cookies did me in.
When I was pg I craved eggs intensely. I decided to add eggs, just until I had the baby. With the first free-range bite I thought, I don't think I'm not going to quit again, and I didn't.
Had some weird health problems after 1st baby. Didn't have access to health care, but an energy healer advised me to eat fish. In 12 years, lots of people had told me "you have to eat meat/dairy/ whatever animal product" but I never gave it a second thought. But at this time, I felt it was true for me.
I struggled with the decision, but I believe it's been right for me. One thing I've come to accept, and embrace, is that we do not all need the same diet. Some can be vegan, some can't digest milk, some have allergies to various proteins, etc. We don't all have the same digestive enzymes, why would we think we needed to eat one diet? So I accept that I need some animal products.
It might be possible for me to be vegan again, with a lot of supplementation, but at some point I think the diet becomes very unnatural, which conflicts with other values I hold. Ovo-pesce-veg makes more sense to me, and as much local food as I can acquire. I'd rather buy local eggs from someone I know than expensive algae from a lake 1500 miles away, processed in a factory somewhere else, and brought to me in a plastic bottle on a truck.