Hello!
It is not abnormal to still be using sharps at 2 weeks. I’ve had it take five times and I’ve had it take two months. I’ve even seen BH sites be very stubborn and never work well at all. I’ve met patients who BH the arterial and rope-ladder the venous with a sharp because that ended up being easier for them than trying to get the second BH formed. I’m only saying this so you don’t get too frustrated with yourself or with his arm. They can be temperamental, you’re doing great on the arterial, hopefully the venous will fall in line soon. If not, he will still get treatment. That’s a good thing.
Is feeling the “resistance” in the venous new since you started trying out touch cannulation? This is still on sharp needles, yes? You have more force and control over the whole needle and the pressure when you’re cannulating by the wings because of the wrist-flick. When you back your hand to the tubing, you mostly are guiding the needle tip. Try switching back to regular hand position while still using sharps and see if that solves the resistance problem. When you feel that resistance fall away, and it feels like a hot knife through butter, it’s probably ready for a BH. Touch cannulation is a godsend on BH.
In general, I mostly touch cannulate, and there are absolutely times where you need to “give it some gas”. The best way I’ve found to think about this is the wings control the whole needle and entry. The tubing controls the tip of the needle and very little else. Needing extra “gas” when you get to the vessel-level but holding by the tubing seems pretty normal to me. If the only thing that changed is where you’re holding the needle, that could be it.
Is his access deeper at the venous site or does he have more meat on his arm there? Or excess skin? Anything that would give resistance? That may also be a part of it. If you think it might be a skin thing, try pulling it tighter before going in.
If you’re forming a BH site with sharps, but having to pull back and change directions several times, you will not be able to get one distinct track. Are you “fishing” in there? If so, don’t! You’re only 7 treatments into using this site. If you don’t know if the track is forming well in that spot, is there another spot you can find that’s closer to the surface of the skin, or easier to cannulate repeatedly with one smooth motion? If so, it’s not a bad idea to start a new site.
Some people do throw a clot to the needle when there has been manipulation going on. Other people throw clots to needles just because the day ends in y and that’s how their bodies work. 
It is frustrating to not know if you’re in the vessel or not because of a clot. You did the right thing by pulling the clot out, and then flushing with heparin.
If he ends up being one of the people who clot needles easily, you can ask your nurse to show you how to do a wet cannulation–that’s when you prime the needle to the tip and the tubing with saline prior to cannulation. Once you’re in the vessel, the saline should prevent a clot from sticking so you can check flows immediately.
I hope something I’ve said helps. Good luck. You’re absolutely acing the arterial site. That’s an accomplishment. The venous is giving you a harder time, but don’t let that shake your confidence. The arterial is coming along nicely–it may not be anything you’re doing.
I have to ask– is your husband physically capable of cannulating himself? Can he reach and see and hold a needle? I am asking because the patient truly tends to be better at this than all of the nurses, techs, and spouses combined. If he can do it, let him. He can feel both ends of the needle, you can’t. I can’t. It might frustrate you both less. If he can’t, then try the rest.
Good luck, keep us posted! Also– if you’re on Facebook, consider joining the Home Dialysis Central Facebook Discussion Group. There are a lot of patients/partners in there, some with a lot of experience with forming BH. You might want to ask in there and see if someone comes up with better ideas than me.