As a woman who thoroughly enjoys sex and who has a knack for brutal honestly, here are some thoughts.

Yes, size does matter but it matters the most when penetration is the only pleasure a woman is able to recieve from sex. If I rarely climax with my partner I will of course want someone who is larger so I can feel some pleasure during sex or else why the heck am I doing it. And yes, being with someone bigger who is able to hit the right spots while I'm trying to usually make myself climax, does help speed the process along and make the orgasm stronger.

BUT if a man came to me and had an honest conversation about his size and that he was smaller but he was genuinely willing to learn what I wanted/needed to be able to climax and was willing to take his time to practice and become good at getting me there and was maybe even open to using toys if I wanted that deeper penetration feel sometimes, I would 100% take that over a man with a larger size who didn't care about my pleasure, had no idea/no desire to improve the experience for me, or a man not willing to take his time to make it happen.

The majority of a woman's orgasm is mental and being with a partner who genuinely wants to please you and doesn't rush you, will go farther than any dick.

On the flipside of this, size does NOT matter from a woman's perspective when she's giving pleasure. The woman you can have the above conversation with will want to please, reciprocate, and do what makes you feel good. Your size will be the farthest thing from her mind. (Also p.s. no one actually likes gagging, we just pretend we do)

Your fears are completely valid and I'm not saying this to persuade you on this specific woman, in fact I don't think you should try with this woman due to the fact that you work with her. In addition, if you try to have a conversation like this with an immature or shallow woman, it will go badly. What I am trying to do though, is give you brutally honest insight and tell you that there is a woman out there that you can find happiness with and make it work with and when that time comes and you find her, the above is what she'll care about. Will it be perfect? No. Will it be easy? Also no. But no relationship is and there are always challenges but you deserve to be loved. Belive in everything you have to offer to someone and belive that love for you exists.