Re: I'm 29 and I am having trouble with ED
Your problem might just be that you masturbate too much. Could you possibly have any callousing on your penis?
I have never met a man who was into using the rings you mentioned for long. They seem to decrease penis oxygenation or something. Some men seem to sometimes like them at first but not for long (more than a few months at most). I think they become increasingly uncomfortable from restricting circulation excessively. I wouldn't recommend using one.
Your problem staying aroused during sex could quite likely be solved by increasing the sensitivity of your penis. There are things you can do to increase the sensitivity of your penis. Usually the first option doctors present is pharmaceutical, but you may want to consider that there may be long-term side effects--especially accelerating the desensitization that comes with aging (if only for the increased friction from actually using the penis more).
Without any potentially harmful effect, you could also try keeping your glans protected from rubbing against fabric in your clothes. This can increase sensitivity quite a bit (reversibly). There is a product called the "ManHood foreskin substitute". It's a little soft fabric pouch to wear over the end of your penis to shield it from rough fabric. Wearing it for a month is said to make a noticeable difference.
Another option you could try is controversial within the American medical community, but it is the most effective thing you can do to increase the sensitivity of your penis: nonsurgical foreskin restoration. (Technically one can't actually restore foreskin but it's possible to regrow something very similar. The foreskin is essentially just a continuation of the skin of the penis. Unless there's excessive dorsal and ventral nerve damage below the circumcision scar, you should be able to regrow new nerve endings in the new skin. You can't regrow the specialized fine touch receptors or all the original connective tissue structure exactly, but nothing else can give you new nerve endings on the most sensitive part of the penis.)
It's obviously a big commitment. It has to be done very gently and very slowly or the skin can tear and scar. It can take a LONG time if there's very little skin to begin with (1-3 years); and it alters what your manhood looks like (when flaccid--with an erection foreskin retracts only making the penis wider behind the glans, so it only appears as increased girth). But foreskin restoration is the only way to grow new nerve endings on the penis. You can read more about it elsewhere on the internet.
There are contraindications like UTI or STD infection, latent infections like HSV,HPV,MC,et al. or the presence of a scarring disorder, so it's worth consulting a dermatologist or urologist before beginning. Unfortunately, the majority of American doctors don't know anything about foreskin restoration, so you'll have to find the rare one who does to talk to about it. (And unfortunately just because a nurse or receptionist says that a doctor can advise you about foreskin restoration does not mean that is actually true, so it seems like you need to insist first to ask the doctor personally whether s/he will be capable of advising about it before you seek--and pay for--a consultation about it.)
One major advantage of foreskin restoration (and foreskin generally) is that because it increases sensitivity, it drastically reduces the pressure that you need to feel adequately sexually stimulated to enjoy sex fully. It will let you feel sex with more nerve endings. Appreciating a lighter touch is useful because high friction sex and especially masturbation can definitely accelerate penis desensitization.
I hope this helps!