But I would definitely love to join your team. I hope you will have an open position when I apply next year.
Done with contractions: (A little less formal)
But I'd definitely love to join your team. I hope you'll have an open position when I apply next year.
Your word order is salvageable with punctuation. I only removed 'and' as a mater of style. Though 'will' and 'for the' are simply not needed.
But, definitely, I would love to join to your team and I hope you have an open position when I will apply for the next year.
Done this way puts a pause before and after 'definitely' that highlights it for emphasis. Which may or may not be what you want.
Some people discourage the over use of
I. Better not to make everything about you:
If you have an open position when applications are accepted next year I would definitely be interested in joining your team.