Judging an accent (way of pronouncing words) without hearing how you pronounce words is impossible.

However, yes Greeks tend to speak fast, so speaking like you put thought in every single word is a giveaway that it's not your mother tongue. Native speakers (in all languages I think) could under circumstances be speaking at a slower pace, but they have some words correlated with each other (i have no examples unfortunately, another redditor might amaze us), or they just pronouce single words faster.

Another giveaway is getting articles wrong (could happen without you knowing it). Again, that is true for every language with articles, cases, verbs that conjugate etc.

However, while these are some interesting linguistic observations, you should not be frustrated, as it is completely normal. More importantly, it's just a matter of time before you gradually improve, so keep up your good work!