Even though I tend to be quite forgetful about writing regularly, it always gives me a sensation of accomplishment when I see all those words written in a language different forom my mother tongue.

They offered a new product, but it didn't felel the same.

I was really glad when I discovered that website, because my favourite part of learning new languages has always been writing.

Even though I tend to be quiquite often forgetful about writing regularly to write, when I do, it always gives me a sensatione of accomplishment when Ito see all those words written in a language different formother than my mother tongue.

What you've written is grammatically correct. However I don't think it is necessary to qualify your first statement so much. You say 'I tend to be' instead of 'I am', 'quite forgetful' instead of 'forgetful', and 'writing regularly' instead of just 'writing'. You can convey the meaning equally well by just saying you often forget to write.
Also, you should say 'when I do [write]', because otherwise it's not clear which words you're seeing -- maybe those of other journal writers?

I began learning English when I was very young,; when I was around 6 or 7 years old in primary school , English was a mandatory subject, but in primary school. However, I only started to make real progress afterwhen I entered college and began to write journals.

Your sentence is confusing because you're throwing so much information into it. I would split it up, and there are many ways to do that. I like semi-colons and dashes, so I might do what I've shown.

I gotwas really sad when the site shut off thequit taking subscriptions and the community started to slowly vanished.

I'm not sure what you mean by 'shut off the subscriptions'.

They offerstarted a new productwebsite, but it didn't felel the same.

I'm not sure what you meant by 'product'.

I hope the community grows large and strong, and I hopeattracts many members. I also hope that I remember to write entries regularly.

By 'grows large and strong', do you just mean you hope many people become members? If not, what do you mean?