May I suggest Valerian Root. It's a sedative. Very mild. One of the main over the counter drugs in Europe to treat anxiety and nervous disorders. It calms everything down in the body and is supposed to help slow down libido IF THATS what you want. I have taken it for other reasons. It's easy to find. I think the Herbal shelf at Walmart even carries it usually. It's best to take at night and do not take it in conjuction with any stimulants. Don't even take it with Saint John's Wort (Herbal stimulant) or you could get the shakes. I did that once. Yikes!
Secondly Echinacea is suppose to support prostate health and I read in one place that it's supposed to help with controlling erections. I don't know for sure how helpful Echinacea would be but I have used that as well - primarily for illness.
Don't drink any of those energy drinks with Ginsing in them since its supposed to increase sexual function. Also guarana root which is technically another high caffeine additive. Caffeine or Guarana increase your blood pressure which in turn makes it easier to achieve erection.
Either of these herbs are relatively safe and beneficial even if they don't accomplish what you are looking for. Just be careful to read all the information on them and use them wisely. If you want to search for more herbal remedies I would suggest a site that I use for personal research.
http://www.egregore.com
On a positive note - I have heard the same that restraint eventually builds up personal energy. It is good for you in moderation. You may learn to control it more and function better in the long run.
I hope these helped. Good luck. Hope you make it.