bettas, I am a little concerned by what you're saying - I do realise some of your fish died and I can't say I'm surprised but, which fish did you 'get rid of' and how exactly?
Please, also, realise that you can't get more fish now, nor later, and that you should re-home or return the siamese flying fox. I suggest you stop asking about what you can add - you can't add ANYTHING - and focus on learning about the fish you already have.
Are you doing daily water changes? You should be.
You need to start taking this a little more seriously. The fish you have are entirely dependent on you and they are living things. Do you realise that? They cannot care for themselves - you are completely in control. They also aren't toys or decorations or something for you to collect. They are living animals and deserve a little more care and respect than you appear to be willing to give.