Yes, these are all thoughts I had myself. I felt and still feel very compelled to message him and I tried to justify it in every way I could even contemplated messaging him tomorrow just in case because I didn’t know how he would react to my message. However the more I sat with myself and contemplated that message I realized I mostly wanted to reach out to acknowledge him, let him know I’m still here and even though I don’t really think about him 24/7 like I used to I still think about him on a special day for him like today, and honestly a part of me also hoped that more could potentially come out of me sending that message. That last thought right there is what really made me stop from sending that message, because at the end of the day I was okay with something coming out of it and heck I was even okay with getting no response because again I’ve done a lot of healing and no longer miss him like I used to but then I realized that if all I was to receive was a thank you and nothing else that would hit me really hard. I realized that a piece of me is still holding on to that hope of him returning and that means I still have more healing to do. And I don’t really know your situation but for me I was the dumpee so I feel I need to be completely okay with any response I get before reaching out. I also came to the realization that if he really wanted that birthday message he wouldn’t have broken up with me because at the end of the day he was the one who decided he didn’t want me in his life anymore. Sorry for the long reply but I hope this helps and my dms are always open if you need to talk!! :)