Hey! Just wanted to say that I totally get where you're coming from, waiting for letter of recommendations is the worst feeling! The way you describe her I don't believe your thesis adviser would be upset with you trying to get into contact, so definitely give them a call just to ask if she is doing okay and if she is available to speak.
If she has happened to drop the ball, I don't think it's too late at all to ask someone else if you have someone in mind. Most professors/supervisors understand that things happen and sometimes need a backup letter of recommendation. You still have a coup