I think giving into the attachment would mean forming a deeper, more meaningful connection with your t. Attachment tends to make one more needy. If you give in to the attachment, you will most likely crave even more contact with t in between sessions. You state you had deeply needed him last week but he wasn't available. What was he not available for (ie. emailing, phone calls) and why (ie. not allowed, on vacation, you didn't feel you should bother him)? How will this unavailability play into your attachment needs?

Attaching to my t was a game changer for me. It's played a major role in successfully getting me out of hell. It's been very helpful to my growth and healing but I couldn't have done it without out of session contact.

Find out what "giving in to the attachment" looks like for you, and what it looks like for your t to make sure you are both on the same page before attaching. Discuss the expectations and find out the boundaries that come with this attachment process. Are you allowed out of session contact with t? How? If you email, will he respond? If he responds, how will he respond in general (in detail, a quick sentence or two, a simple acknowledgement he received the email)? Will boundary changes be discussed before being implemented? Can they be taken away without warning? Just know as much as you can before letting yourself go because attaching requires a lot of trust. Knowing helps.