If you are going to a decent clinic you will be reducing all the fears you have, from not liking the result to not working. Which if the clinic is decent is probably the least likely of your scenarios. That said, it is a very personal decision, and in some aspects, the clinic or doctor has very limited input. Your expectations and happiness threshold.
It´s important to be realistic, and try to see grown-out, healed FUE results, if possible in person. Also with similar hair and skin characteristics to yourself. Discuss with the doctor their plans for harvesting the grafts, the pattern they use, and whether the extraction is spread or condensed. Unless an extremely large procedure, spreading the extraction over the widest area will minimise any obvious or noticeable scarring, even with shorter hair. It may be noticeable, but more likely only to yourself. Who will be the biggest critique obviously.
Try to minimise any concerns such as ongoing hair loss. I believe you use/d finasteride. Look at your family's hair loss history. If there are many cases of advanced hair loss, and judging by your age. Take a common-sense approach to your starting restoration and the future. While there can be no total assurances you can minimise your concerns. If you are still very unsure there is always another day to research before deciding. But, bear in mind. It is quite normal to have concerns, in fact, it´s slightly unnatural not to. Good luck.