I had an HSG done on day 5 of my cycle. I took 2 extra strength Tylenol before so the "Ibuprofen delaying O" idea doesn't work for me. I have a longer cycle- 32-26 days, more recently it has been a steady 33-34 days. I have high FSH, but also high AMH. I usually ovulate anywhere from day 17 to day 19, but never after. I started using the Clearblue Advanced Ovulation stick a little early as I had read that the HSG may cause me to O early. Got two negatives on days 11 and 12, and "high" readings from days 13-18. Never saw a peak so I didn't know what was going on. Got a "low" reading on day 19 so I didn't test on days 20 or 21. Starting feeling O pains on day 21 and seeing EWCM, which I had not seen until then, which is weird for me. I tested on Day 22 and got "Peak" reading. So yes, it did make me O late. I knew something was up b/c I have strong O pains and didn't start feeling them until day 21.
Hope this helps...