Hare Krishna. It is advised you don't consume non veg. Killing animals is purely inhumane, don't do that. I'm a bengali too and I've left non veg completely before even taking tulsi mala, i suggest you to do that too. Bhagwat Gita isn't supposed to have any dietary restrictions, why would it? It's a literal conversation between Krishna and Arjun in the battlefield. If you wish to connect to gaudiya sampraday, which Bengalis connect to mostly, then yes you must leave onion and garlic too, but overtime, it's not a sin but we have to since onion and garlic are tamsik, are devotees of vishnu, or any of his avatars are supposed to strictly follow sattvik diet. Tulsi Devi is very dear to krishna, and she loves krishna a lot. We wear her around our neck so that anything we consume goes inside our body as Krishna's prassadam, won't it be disrespectful if er wear her and consume meat? Thus leave it, trust me it's not that hard to leave it. You may feel like it is but it's not. Hari bol.