Envato the best place for getting help.
Happy to make some recommendations. What sort of issues are you having with the mobile checkout?
I just had a quick play with your website via my mobile. It’s responsive, which is a tick. I didn’t have too much trouble selecting the product and starting the checkout process on my end.
If you can let me know what you’d like to improve upon and the kind of features you’re after, myself or the community can probably point you in the right direction
Feel free to contact if you’re looking for a paid solution: