Beginner trying to pack tube but doughnut is interfering

[PumpingAus]

Hey everyone, I'm looking for some advice.
I've been pumping for about a month now with a proper tube and hand pump set up. I've got a size matters tapered 1.75" as I measure about 5" circumference unpumped. I keep the pressure below 5hg mostly with the odd 20 second spike up to 6 or 7. My foreskin is intact and I have a meatotomy.

Since very early on I've had donut blowouts and I'm only ever packing the base couple of inches, even after 2 hours. My donut and glans presses hard against the tube walls. I figured this is actually stopping my shaft seeing pressure so I started with a silicon tube down the side over the past 2 days to try and get myself properly packing by equalising the pressure in the tube.
I'm still getting a really big(1/4") space at the base on the underside where it just doesn't want to fill out. You can see it in my second pic. I'm definitely packing more of the shaft otherwise but want to get the whole lot packed.

Do I just need to persevere with the silicon tube a while longer because these parts of my penis haven't seen much pressure before? Should I get an untapered 1.75 or even downsize to a 1.5? Anyone got any tips or tricks? Thanks in advance....

P.S: those pics are taken 90 minutes into a session, with breaks for massage etc.

[PumperSoCal]

Using a tube like that is actually the exact thing I do to make it so I can pack uniformly. Once my shaft catches up I just pull it out. It takes time for one's shaft on most guys to catch up to the foreskin, which always bloats up faster than the rest of the shaft will. Tapered tubes do help in this manner in my experience as it tends to push the growth towards the head as you pack and is good for helping build a "base." At least to me it is. Just keep at it. It will take time to build up your base to pack more uniformly.

[PumpingAus]

Thanks SoCal.
I think you're right. I only discovered the tube trick a couple of days ago but I've been pumping for about a month or a little more. The past few weeks my head and foreskin have packed the cylinder so quick and I think it was causing a low pressure area below it.
The past 2 days of pumping with the silicon tube in place have left my upper shaft slightly discoloured, whereas the rest of my cock is fine. I think that area just hasn't been seeing much pressure until now that I've got the silicon tube to equalise it. My doughnut hasn't expanded as quickly using the silicon tube in my pump tonight and it looks like I'm packing a bit further along the shaft than previously. So like you say I think my whole shaft just needs time to get used to it.

It's reassuring to know the tapered tube wouldn't be the issue.
Thanks again for your help.

[PumperSoCal]

That's great! I'm glad it seems to be progressing well and that seems to be working out for you. Also during breaks massaging from the base towards the head also will help disperse fluids throughout your shaft too and it will help the uniformity build a bit better. It's a lot of time and experimentation to try and find out what works for you. When you hit your "sweet spot" that's just right for you is the addicting part in my opinion. Once you fully pack in those tapered tubes girth wise, at least for me, it started to feet uncomfortably tight, like not a good type of stretch. So if you feel that kind of achy or flat out unfcomfortable, I'd suggest moving up to a 2" taper if you still like that, but I'd suggest moving to a straight tube too if you can. They produce more volume obviously.