When I was a flight attendant women would ask me to hold their baby while they used the toilet, situated their bags, collapsed their strollers, etc. I never cared and every time i've flown with my ds the flight attendants have never had a problem helping me.
When I was a younger mother, I travelled with my kids by myself quite often. My two youngest were quite close in age, DD#1 was 14 months when DD#2 came along, and very tiny still at the time. For awhile I had both girls in the infant carriers that you wear on the front. In order to go to the bathroom in public I used to have my oldest (DS), then 5, hold the youngest on his lap in one corner of the cubicle while I still wore his other sister. Not comfortable and definitely awkward to say the least, but it was doable.
The same can be done flying. Just wear baby that way your hands will be free to a point. You may want to practice at home first before trying on a plane though. And yes I did have to do that a time or two on a plane. DS was an accomplished flier by the time he was 6 months old, and I made a few trips cross country with him by myself.
I have traveled alone with both of my kids. First was my oldest when she was 6 months old (jest her and I). The second time was with my youngest 1 week before she turned 3.
With my oldest (when she was 6 months, I managed to hold her and pee at the same time. Not easy but do able. Wear pants that don't have a botton and can just be pulled down and up with one and. I wear a pair of dress pants with an elestric waist.
My 2nd time, I hald my oldes until the door was colsed, turned around and sat her down on the floor, (she was standing) did my thing then picked her up to open the door. It was a little tricky but was doable.
Stewardess. They rule. They are there for help. They don't mind holding baby. I travel alone three times a year since my son was 5 months old. He is now 4. I am like an experienced solo traveler.Just don't overpack. Do not pack a stroller unless absolutely needed. Baby wear and check your storler like luggage.
I've flown internationally with baby and toddler...a few times the flight attendants would watch him, and when he got bigger he could stand in front of me...they have changing stations to change baby, but always bring extra diapers! I don't know how, but my son always manages to pee/poo a ton every time we fly!! I blame it on the altitude!!! and I also suggest wearing a pad or panty liner....because you never know when you can't wipe well enough, or when you are holding it for just a little too long!
OH and another suggestion...IF you have baby in the bathroom with you....open the door a tiny bit before you flush! My son FLIPPED every time I flushed b/c it is so loud, so I would unlock the door, flush with my foot, and leave asap so he wasn't as bothered!