dd is 4 months, she doesnt like lying on back on playmat, constantly trying to sit herself up and making disgruntled noises we have a bouncy chair which she only goes in when having a quick nap (comfy lie back one) , she likes door bouncer for short periods. She basically likes sitting bolt upright on my knee all day , and i am finding it a bit difficult to get anything done in the house. would a bumbo be a good buy? it seems a lot of money? how long can they be used for? or would i be better with a highchair and some how wedging her in it with cushions?