Erection problems 26yo male

Hello,
I am a 26 year old male. I have type 1 diabetes and have had it for 4 years now. Starting around 2 years ago I started noticing problems with my erections. Not as hard and start to go away once the hard work of sex sets in. Recently things seem to be getting worse. I hardly get morning erections anymore whereas before I used to get rock hard erections when I woke up that wouldn’t go away. I almost can’t at all get an erection good enough for sex and if I do it will go away once any movement starts. I also have a much lower sex drive than I used to. Also, it now takes me a lot longer to ejaculate, maybe even too long, where as a couple of years ago I always ejaculated very easily and quickly.
Last night I tried Levitra, and I took half of a 20mg tablet. This made absolutely no difference. I expected it to give me a rock hard erection like I used to have a couple of years ago but no, no help at all.
I think my diabetes is reasonably well controlled. My hba1c is usually in the low 6s, like 6.3 – 6.5. Although I do go through stages where my blood sugar always seems to be up around 15mmol/L. For about a 3 month period starting around 6 months ago I know my control was bad because I lost weight despite eating lots and doing little exercise. I am not however overweight and never really have been.
I am not sure it is related to the diabetes as the doctor seems to think it isn’t. I have only had the diabetes for 4 years and it usually isn’t a problem in type 1s even if they’ve had it for a lot longer than me.
After the table didn’t work last night I am really depressed about this as I feel there is no hope for me now. I feel that I can never have a girlfriend or a wife now and am going to end up alone. If it’s a problem at 26 what hope do I have at 50? If anyone can offer any advice or help it would be so greatly appreciated.
Thanks.