It looks very much like theft. But the “theft prevention person” could have waited until you came to the register, where you would either have paid or removed all doubt that it is theft.
So if you were indeed “walking to a register”, or even “queuing up at a register”, your lawyer could argue in court that there is reasonable doubt of your guilt, which would have gone if the theft prevention had just waited a moment.
A similar defense could work if you had items with clear anti-theft measures. People would be unlikely to hide things in their hoodie that give an alarm if you leave the store.
Another possible defence would be if they have CCTV footage, or your lawyer just asks the theft prevention person, whether you acted absolutely openly without trying to hide your actions - that is a little bit more doubt that you are a shoplifter, because a shoplifter would try not to be seen.
These defenses may or may not work. Either way, hiding things in your hoodie is a very bad idea. To your original question: It is not theft, but you may very well not be believed and be convicted of “committing theft beyond reasonable doubt”.
(In other countries it is theft if the item leaves the store without payment. That leaves much less room for “reasonable doubt”. There is also very little room for "attempted theft". If I try to kill someone but fail, it's not murder but attempted murder. You would think the situation described would not be theft but attempted theft since the attempt failed, but that's not what the law says).