You may also need control of nasal & oropharyngeal space w/ oral device. Consider having a provider construct a hybrid osa oral orthotic initially in phonetic bite titration prn. It can hold nasal canulas fitted precisely to each sized nares.
If haven't already also ck for UAR including nasal valve collapses. Ck for aspirin allergy in that it will cause & exacerbate existing nasal swelling; milk & bread also a potential if UAR present. Xclear nasal spray (nonsteroidal) & Mute nasal dilators may also help.
Try valerian root + melatonin at night for sleep aid. Day time energy cordyceps,
rhodiola rocsea will help. Seems you may also benefit from nutritional counseling which may narrow down potential food allergies as well as the other benefits.
If you a mouthbreather you've most likely already damaged the condyles & must address UAR w/ non-steroidal sprays e.g. Xlear & cones, mutes or similar. However you should address TMJ's using a healing orthotic for eating in for a short period while hopefully having success w/ an ent treating the etiology = UAR & now OSA.
If you must resort to boil n bite oral appliances, don't randomly jut the jaw forward but try to mimic an attained position of the 'S' syllable, this will give a much better balanced relationship & account for existing cant mal-developed. Also suggest that positio as a beginning titratable position if a dds making it!
If you are a mouth-breather you are likely posturally adapting the entire body due to xcv forward head posture thus with cervical-sacral problems are there also.
Fix the nose, upright the head, manage the TM resultant from MB for years & don't exacerbate TM with too much mandibular advancement by yourself or "sleep" specialist! You shouldn't need to dislocate your jaw back to pathological position after using an oral OSA appliance each morning!