From the VERY infrequent dosage (3 times), I am certain that what you are feeling is in no way related to propranolol "withdrawal."
I am going undetr the assumption that you are NOT taking the XL or XP version (or whatever they call the long-acting version, LA?) and just taking propranolol "straight."
I think it's NOT a goood drug for anything other than very short term anxiety, in fact, it's prescribed for "stage fright."
I've taken it on and off for a very long term and I think that unless you are taking it for angina or tachycardia, that 60 or 80 mg. is too much and 10 is perhaps too little. Stick woth the 20-40 mg. doses. I found that taking it in the evening is very hard on a good night's sleep...seems paradoxical... so I NEVER take it after 5 PM.
Propranolol is also a great drug for migraine prevention (and for me migraine abortion.) It is the ONLY beta-blocker that will allow one a good exercise tolerance.
For straight-up anxiety, my favorite medication is 5 mg. diazepam (Valium.) Why not give that a try instead?