Well, first of all, if you are having periods at all, then you SHOULD be ovulating. There are some rare cases where you still have "periods" if you don't but they would be highly irregular. (like 30 one month, 65 the next) So, my initial assumption is that if you are having periods, you are, in fact, ovulating.
I have been temping for almost 2 years now, so I consider myself somewhat knowledgeable in this area.
When I first got started, it was the same thing, I had mountains all over the place. Part of it I think was just due to recently being off BC and so on,t he other part was that I probably wasn't doing it right. First rule of temping is to choose one method of temping and stick to it, never change. I have always done it orally, despite being a mouth breather and I haven't had an issue with it. I can still pinpoint ovulation with no issue.
Second rule, always and I mean ALWAYS, without fail, take your temp at the EXACT same time each day. I tend to get up at random times (especially now that I am unemployed/working freelance) so I take my temp at 6am, 7 days a week. Then I go back to sleep. I would suggest doing the same. Pick a time that is earlier than you would ever normally get up (but still 3-4 hours after bedtime).
Third is when you temp, you can not move, not even to get the thermometer, so it keep it really close to you. Within arms reach. Moving affects your temp. Also, be sure you arent drinking water or anything first, that also affects it.
Other than that, things like drinking the night before, or restless sleep or being sick will affect temps as well. So, I tend not to temp during those times because it's never going to be an accurate temp.