Can LLLT actually increase hair loss and make it worse?

LLLT cannot make your hair worse, genetics and aging do. its likely that even after the LLLT you continued to progress beacuse you didnt do many other things that are needed to slow down the process or you maybe a candidate for transplant.  Start the over the counter grwth factors and pills (see link) and then get a biopsy by someone experienced.
I suggest a formal consultation as there are a combination of treatments that can be done to improve har loss.  Oral finesteride has very little to no side effects in the majority of people; PRP/platelet-rich plasma + stem cells like A Cell help regrow hair and slow down the thinning process; rogaine and restorsea spray should be used daily; oral viviscal helps keep nutrients high in the follices as well.  Transplantation is a last resort but works early in the aging process as well.  A formal consultation and combination treatment is needed.  Best, Dr. Emer. 

It is possible that you have a device that is giving off too much heat which can lead to follicular damage (though unlikely). If you are noticing a marked increase in thinning in a short period of time, it is worthwhile to do a full medical work up with blood work to ensure that there is not another cause for your hair loss such as hormonal changes, thyroid concerns or autoimmune conditions.

LLLT has not been shown to make the hair loss situation worse, possibly your situation was worsening when you use the helmet.