A train question!

please if the answer is obvious don’t make fun i have anxiety and i’m too scared to call and ask and there’s no straight answer online 😅

i have an off peak ticket booked to go from chesterfield to bournemouth on the 11th August at 4pm-9pm. i want to get this exact same train except two days earlier on the 9th August. My ticket says off-peak return valid until 11th August, does this mean i can just get on that train a couple days earlier? It says off-peak aswell but on trainline the ticket i picked doesn’t say off-peak in the corner but i have an off-peak ticket so i’m just a bit confused, help please?

that’s the train ticket i bought, it’s not an off peak train but i have an off peak ticket^^^^

this is the train i want to get, it doesn’t say off peak either but it’s cheaper so idk ^^^^

sorry if this is a stupid question! i’m just genuinely too scared to call and ask 🥴

and i know this isn’t exactly the app to ask on but this is the only app i ever post on and it’s anonymous i feel stupid asking my friends lollll