How to keep running?

You need to build your endurance. I was the same way! I would never be able to run 2 miles non stop. Not anymore. I do 2.5 non stop. Easy.
Here is what you need to do:
1) Choose your comfortable speed, mine is 5mph, even though it seems like a slow speed to some runners, it's still running.
2) Take your walking breaks but have them shorter than running intervals, you'll see you'l manage to do as well as 50/50 breaks if you do 30/70 (walking/running)
3) Practice! By shortening your breaks you'll see how you'll get better.
I used to think I am the worst runner in the world and I am not even that heavy (150lbs at 5'6"). You'll earn your endurance exercising often. Than you'll want to go for longer non-stop runs. Sometimes it's just in your head, you think you're too tired and going to collapse but push yourself for more and you'll see that you CAN!
Good luck!

I tried running for 60sec and walking 90 and was able to do an hour and around 3miles lol I know that doesn't sound like much, but for me it was a huge milestone. All uphill too!

You're in a good place to build on at the moment, but I would suggest that rather than continuing on that path you start focussing on increasing your running intervals, and as a result you'll knock out the walking intervals. You can do that by steadily increasing your time running over time.

You could just do it on your own, or you could use an existing structured programme to do it. Upthread there has been the Couch to 5K suggestion, and what you just described is the interval routine on week one of that programme, albeit for a shorter time. That'll get you to 30 minutes of continuous running, which should be around 3 miles or therabouts; 5km. At the end of the programme it'll take some longer than 30 minutes, but you're starting from a position of hvaing the capacity for longer duration, so you could be able to finish 5k in 30-35 minutes.

From there, you can increase your distance, or work on your speed, or both. Personally I consolidated for a couple of weeks then started increasing my distance.

As you go through a plan it may be that you find the running periods a challenge, in which case slow down a little until you are comfortable. It's more important at this stage to increase duration, speed wll come in time.

I trust that helps, but I would recommend using something like C25K, you may find the group on MFP useful in terms of sharing experience and gaining feedback.