Flying with a little extra weight?
WOW you have just a LITTLE extra weight. ADMIT IT you are large in the seat and find the standard seat uncomfortable. GUESS WHAT your seat is too large for the standard plane seat. You could fly business or first class and get a larger seat. You can ASK the special needs AGENT to assist in your booking. Not hard to book three seats together and you and mom share the empty seat between you. If it is just MOM than the special needs Agent can arrange to have an empty seat next to MOM. Depending on Airline this seat may be free or an additional charge. The SPECIAL NEEDS agent for the Airline will explain it to you. Expect to be on hold for a while. You are not the only one flying that has special needs. BE HONEST when discussing the situation. INCHES between arm rests is what counts not the number of pounds you are , your height, your age the destination or any thing else. LOTS can be done to make the journey comfortable for all when you ASK in advance and explain HONESTLY the situation and your requirements. It is good policy to confirm your arrangements a day or two before travel. Of course while in Miami you will have made sure that the taxi, hotel shuttle or whatever can deal with the size you are.
Maybe ask her to sit by the window if you are in economy. That way you won't be squashed in between the window and her. Get an aisle seat. Book the ticket yourself and ask the agent to give you those seats without her knowing.
SSP Bowl Dude
Business class has wider seats than coach and first class even wider.
Either buy a first class seat or two regular seats (in most planes you can lift the arm-rest making for a wider seat).
Buy first class seats. If you cheap out, you will regret it.